Process of producing solid fuel briquettes

Oct. 15, 1935. _G komarek et al 2,017,402

PROCESS OF PRODUCING SOLID FUEL BRIQUETTES

Filed Aug. 3, 1933 2 Sheets-Sheet 1

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Oct. 15, 1935. g. komarek et al 2,017,402

PROCESS OF PRODUCING SOLID FUEL BRIQUETTES

Filed Aug. 3, 1933 2 Sheets-Sheet 2

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Patented Oct. 15, 1935

2,017,402

UNITED STATES PATENT OFFICE

2,017,402

PROCESS OF PRODUCING SOLID FUEL BRIQUETTES

Gustav Komarek and Walter 3. Chapman, Chicago, Hl., assignors to Komarek-Greaves and Company, Chicago, Ill., a corporation of Illinois .Application August 3, 1933, Serial No. 683,540

Claims. (CI. 44—15)

Our invention relates to briquetting and particularly comprises an improved method for the manufacture of briquettes of the smokeless type.

Since the making of fuel briquettes became an 5 industry, the desirability was recognized of limtiing the amount of smoke producing binder to the quantity necessary for making the briquettes impervious to moisture and adding non-smoke producing adhesives as the principal binder to create 10 strength. Many attempts have been made to produce smokeless briquettes, but the use of nonsmoke producing binders as a primary adhesive has been limited because of the attendant difficulties occasioned by the requirement that mois15 ture or water be present before such binders can perform the expected function.

The present invention recognizes (1) the demand of the trade for smokeless briquettes, (2) the very limited production at the present time 20 of smokeless briquettes, and (3) the difficulties which have heretofore discouraged the manufacture of briquettes of this type and in fact, forced the briquette industry to resort to smoke producing briquettes in order to yield a profit.

The smokeless briquettes of the present invention comprise a body mass of combustible material having as its primary adhesive and in some cases its sole bonding agent a non-smoke producing binder. We have discovered a novel method of 30 heating and conditioning the combustible mixture prior to briquetting which is (a) commercially feasible and (b) results in the production of briquettes which are firm and resistant, having a high calorific value and the required smokeless 35 characteristics.

This method consists in bringing together a solid fuel combustible and a binder and initially spreading the latter under conditions to prevent premature hardening of the binder, continuously 40 conveying the binder and combustible along a predetermined path and simultaneously agitating the mixture to spread the binder and heating the mixture along a portion of its path to render the binder adhesive and the mixture plastic. 45 Thereafter, along the remainder of its path the mixture is agitated and tempered, for example, by. passing through a non-heated area when the binder is conditioned to optimum adhesive state . and a final plastic. briquettable mass is formed. 50 This briquettable mass is directly briquetted in the usual briquetting machine.

The method which we employ is continuous and controllable. The raw mixture is first heat treated and conditioned, and then delivered to the 55 briquette machine or press from the heat treating conditioning means in a final state, as regards plasticity, moisture content, and temperature, and with the binder exerting its optimum adhesive effect. This final plastic briquettable mass is obtained regardless of. the combustible employed and ύ its condition, for example, its moisture content, and likewise the nature of the binder or binders employed whether aqueous or non-aqueous is immaterial. The final plastic mass delivered to the briquette machine is so conditioned that the 10 briquettes ejected from the press are finished. They require no further treatment and are ready for commercial distribution or consumption.

Stated briefly, the method of the present invention is not limited by the characteristics of the 15 ingredients of the briquette nor the presence of moisture or water. It essentially comprises a heat treating and conditioning of the mixture prior to briquetting whereby to render the mass in a final briquettable state. Neither preliminary 20 drying of the combustible or preliminary treatment of the binder is necessary, and as stated, the final product delivered from the briquette press is a complete commercially acceptable article.

In general, the use of non-smoke producing 25 binders of the glutinous or starch bearing type has required the provision of a carrier such as water acting as a solvent or dispersing agent. The object of such an agent is to assure as far as possible spreading and contact of the binder over the 30 comminuted combustible material and to render available the adhesive properties of the binder, that is, soften the binder and dissolve and disperse the active adhesive principles. With a starch containing binder, the solid fuel combustible 35 binder and water are brought together under conditions to prevent premature gelatinization of the starch and the mixture is continuously agitated to spread the binder over the combustible and is simultaneously heated, the temperature being 40 controlled to remove excess water and bring the binder to an adhesive or gelatinized state forming a plastic briquettable mass. We find that more complete solution or dispersion of the binder in water is obtained if the combustible mass con- 45 tainihg the carbonaceous material, binder and moisture is given a heat treatment, i. e., a cooking and simultaneous agitation. That is, the water normally tends to soften and dissolve the bonding agent in the case of a soluble binder and to soften 50 and disperse the bonding agent in the case of an insoluble binder. The amount of the active principles dispersed, or dissolved in this manner is, however, greatly increased, in fact is quite complete, and the softening, dispersion or solution is 55

2,017,402 materially quickened by a cooking operation. This cooking and agitating operation, moreover, in addition to bringing out the optimum adhesive properties of the binder and accomplishing effi5 cient spreading of the binder, will also act to concentrate the binder by reducing the amount of moisture present and at the same time, eliminate from the combustible mixture such an excess of moisture as would preclude the formation of the 10 finished article in the briquette machine.

We have referred to a cooking of the binder, and by cooking, we mean the heat treatment and conditioning of an aqueous solution or dispersion, or other spreadable bonding agent, for example, 15 a non-aqueous one having potential adhesive properties. The invention is therefore not restricted to treatment of aqueous solutions or dispersions and can be employed with equal facility where the bonding agent is non-aqueous. The 20 cooking operation in either case will act to bring out the optimum adhesive qualities of the particular bonding agent and moreover, will concentrate the particular binder to its maximum state of adhesiveness in the final briquettable 25 mass. Furthermore, the temperature of the combustible mixture and the activity of the binder is such that it will exert its adhesive effect to strongly bind the particles and form a firm, tough briquette and this will be accompanied by a rapid curing 30 of the briquette and setting of the binder substantially within the time cycle of the briquetting operation.

As stated, it is usual with non-smoke producing binders to form an aqueous dispersion. In 35 such cases, the water or moisture employed is considerable, as for example, with starch bearing or glutinous materials which are preferably smokeless binders, water Is often employed in amount as high as ten parts to one part of binder. 40 Such an amount of water in a mixture of combustible and binder produces a soggy mass in which the binder is in a very weak state of adhesiveness.. With the present invention, the binder is preferably introduced dry into the combustible 45 which either has a moisture content sufficient to form a paste, or water or moisture is added to the mixture to obtain the desired spreadable dispersion or solution. That is, the moisture may _x be present in the combustible or supplied thereof) to in amount whereby cooking of, the mixture will bring out the maximum adhesive properties of the bonding agent and render them available. In some cases, the binder paste is first prepared and supplied to the combustible but this is not pre5 ferred, since it is unnecessary and adds an additional step to the method.

The combustible and binder are kneaded and mixed in a chamber having a paddle mixer or other suitable mixing conveyor. The chamber is 60 positively heated for a portion of its length and the mixture is treated while travelling through the chamber in a direction away from the heated area. That is, the mixture is agitated by the paddles and simultaneously passed thereby progres65 sively and usually at a relatively slow speed through the chamber, first, in the positively heated area and second, in a non-heated or tempering area, from which latter it is delivered in final briquettable condition to the briquetting instru70 mentality. In this maimer, the cooking of the binder is accomplished' simultaneously with its thorough dispersion and contact with the com. bustible. Again, the moisture content of the mass is reduced so that from an initial soggy mixture 75 with the adhesive in a weak state, the mass is pro gressively formed into a plastic state having the precise quantity of moisture essential to maintain the adhesive active and the mass plastic. Moreover, the continuous movement of the mixture through the heating chamber with simultaneous 5 agitation completely heats the combustible and the binder to uniformly condition the ingredients and in the tempering area, the heated mass is further conditioned to its final briquettable state so that it is discharged from the tempering area 10 in a heated condition exactly correct to assure quick self-curing of the briquette and setting of the binder.

The continuous treatment in the chamber provides for (1) cooking the diluted binder solu- 15 tion or mixture so that the binder exerts the optimum binding or adhesive action and (2) reducing the moisture to a negligible amount consistent with assuring that the binder will be active and the mixture plasticized to a state most suit- 2( able for briquetting. This is accomplished by the initial heating and agitating of the mixture and then the immediate or continuously subsequent treatment and agitation of the heated mass in the tempering area. There is thus obtained a pro- 21 gressive and controllable treatment in which the speed of travel of the mixture through the chamber, the rapidity of the agitation, and the temperature applied to heat the chamber are controllable to obtain the final briquettable mass. 30 The mixture delivered from the tempering area is in ideal briquetting condition and (1) is free from sogginess, and (2) the initial weakened state of the adhesive is entirely overcome since the adhesive is in its optimum state of activity. 35

Moreover, as briefly pointed out heretofore, the final plastic briquettable mixture is hot so that the briquetting action will result in curing the briquettes. In other words, the final mixture fed from the tempering area to the briquette machine is hot 40 enough, 1. e., it) is uniformly heated throughout the mass, whence the briquettes are self-drying and the binder is set substantially during the time cycle of the pressing operation. The negligible moisture present in the hot mixture is dissipated 45 and the extremely active state of the binder assures that the binder will set rapidly and the briquettes ejected from the press will be hard and resistant. They are ready for distribution and consumption and neither conventional air ⁵⁰curing or positive heat treatment are required. In stating that the setting of the binder and the curing of the briquette takes place substantially within the time cycle of the briquetting opera- _6δtion, we mean within a period of time which normally transpires from the delivery of the briquettable mass. from the tempering area to the briquette machine, its formation into briquettes in the machine, and its delivery therefrom. The 50 briquettes taken from the briquette machines can be safely handled without fear of squashing and can be shipped or stored or consumed immediately, since they are tough and integral. It should be pointed out here that the regulation of the 65 precise amount of moisture necessary and the rendering of the binder in its most effective state coupled with an appropriate temperature of the mass delivered to the briquette machine eliminates all necessity for any expensive subsequent 70 treatment of the formed briquettes.

It will be observed that the finished briquettes of the smokeless type are thus obtained by what is essentially a two step operation as distinguished from the conventional unsatisfactory and expen- 75

2,017,402 sive methods wherein the steps of (a) preliminary drying the combustible, (&amp;) the formation of a weak soggy mass, (c) the briquetting of such a soggy mass, and (d) subsequent heat treating 5. of the squashy articles so produced, are considered vital. By a two step operation, we mean (1) heat treating and conditioning the mixture, and (2) briquetting to produce the final article. In the conditioning of the mixture, the heretofore in10 superable difficulties incident to a presence of , a diluted and hence weakly adhesive binder and excess moisture are overcome. By agitating the mixture during travel through the heating-tempering chamber, these two factors are cared for, 15 and at the same time, all parts of the combustible are uniformly heated, and the binder is likewise uniformly cooked to attain its maximum adhesive state. This producing of first a final plastic briquettable mixture at the correct temperature 20 for briquetting, as explained, and then briquetting to obtain the finished briquette without need of subsequent heat treatment or other conditioning of the briquettes, renders the invention successful both from the standpoint of obtaining 25 satisfactory briquettes having negligible smoke producing characteristics and from the equally important practical consideration of a commercially feasible method of manufacture.

The advance represented by this invention will 30 be understood from a brief recitation of the objectionable and expensive practice now followed in making smokeless briquettes and which has discouraged the manufacture of the product except to a limited extent in localities where its 35 present high price can be absorbed.

Smokeless briquettes are now made by first drying the combustible to remove the moisture, a step obviated by this invention. Then a prepared binder paste is added to the combustible and 40 mixed therewith forming a soggy mass having the binder in diluted condition therein and which thick soupy mixture is supplied to the briquette press. Because of the high percentage of moisture in the mixture, it must necessarily be weak 45 and soggy. Moreover, by reason of this dilution, the binder is in its least active state; i. e., it exerts a very weak coefficient of adhesiveness wholly inadequate for the purpose of a briquette binder. Where the combustible is not pre-dried these con50 ditions of sogginess, weak binding effect· and excess moisture are aggravated. This thick soupy mass of uncertain bohding characteristics is difficult to handle and control as contrasted with the self curing and final plasticized briquettable 55 mixture of the present invention. It is now briquetted, forming soft mushy articles which must be carefully handled to prevent squashing, and then given a final curing. In view of the excessive moisture, the drying of the formed bri60 quette and setting of the binder can only be practically accomplished by a positive heat treating. The necessity for a pre-drying of the combustible and particularly this final drying operation of the formed briquettes have been the serious draw65 backs to^; commercial production, for the reason that the drying equipment required is alone more costly than the expense of all equipment employed for making the raw briquettes. Moreover, the final positive heat treatment of the briquettes 70 extends the time period of operation and is uncertain in that it often develops cracks and fissures in the briquettes.

The conventional process just described is therefore generally prohibitory because (1) ex75 pert cafe is required, (2) the cost of equipment, the fuel expenditure for the heat treatments is heavy, and the time cycle renders the manufacture of smokeless briquettes unprofitable, and (3) the results are uncertain and sometimes imperfect. 5

The present invention is distinguished from conventional practice in that (1) preliminary drying treatment of the combustible is unnecessary, for example, a wetted carbonaceous material from a washery or storage, or a dry car- io bonaceous material or an insufficiently wetted carbonaceous material may be satisfactorily treated to form the combustible mixture; (2) the binders employed may be aqueous or non-aqueous and are preferably fed to the treating chamber in 15 a dry or relatively dry condition, although they may be fed in pasty or fluid form, for example, glutinous and starch bearing materials such as flour, tubers macerated and having their contained moisture, Portland cement, and oily sub- 20 stances may be fed to and mixed with the combustible without preliminary treatment, regardless of· their condition of dryness, wetness, or fluidity; (3) the mixture is prepared and conditioned in one operation wherein (a) the adhesive 25 is efficiently spread and cooked with the combustible to render available its optimum bonding principles, (b) the heating of the mixture is controlled to assure precise cooking and concentration of the adhesive, (c) the heating of the mix- 30 ture is controlled to eliminate excess moisture from the mass and to impart to the plastic briquettable mass a temperature to assure rapid self-curing of the briquettes and setting of the binder in an economic time cycle, (d) the mois- 35 ture content is controlled (moisture being added where that present either in the combustible or in the binder is insufficient to allow cooking or spreading of the binder), and (e) the amount of the combustible mixture, the speed of its travel 40 through the heating and tempering areas and the temperature are regulated, so that the heat treated and conditioned briquettable mixture is hot enough to be self-curing and moisture is present in amount to maintain the binder active and the 45 mixture plastic, as distinguished from a soggy mixture with the binder in a weak state of adhesiveness and requiring positive heat treatment of the formed briquettes; and (4) the final plastic mass is delivered to the briquette machine and 50 briquetted, forming a hard uniform briquette ready for distribution or consumption without further drying or heat treatment. The method is a simple one and easily controllable, and smokeless briquettes of high quality having a maximum 55 of non-smoke producing binder, and a minimum of smoke producing ingredients are made without large outlay for equipment, and in an economic time cycle.

We have discovered that with certain car- ⁶⁰bonaceous materials the particles exhibit a tendency to repel each other. This condition persists in the final briquette apparently regardless of the binder employed, and becomes objectionable when the briquettes are put in a furnace ⁶⁵and start to burn. That is, when such briquettes are placed in a furnace, this repelling action appears to cause the briquettes to open in many places or shatter. To overcome this condition, we pass the hot briquettable mixture from the ⁷⁰tempering area between rolls preferably of metal which may or may not be heated and. reduce the mass to a thin sheet-like formation. The sheet is frangible, easily breaks up, and is collected in the briquette hopper. It is then pressed into ⁷⁵

2,017,402 briquettes which we find are not subject to the objections of shattering, but hold their shape during combustion until completely consumed in the fire. Apparently the repulsive forces are due to electrical charges on the particles which are discharged by the rolls.

The invention, moreover, makes possible the use of a large number of excellent non-smoke producing binders, some of which are novel to the briquette art.

In the accompanying drawings:—

Figure 1 is a diagrammatic view of one form of apparatus employed;

Figure 2 is a similar view of a modification;

Figure 3 is a section of a briquette produced by using certain materials wherein the particles exert a repulsive action to each other;

Figure 4 is a detail view showing the voids between the particles in such a briquette;

Figure 5 is a view of a briquette in which this difficulty has been overcome;

Figure 6 is a composite view in end elevation of a strip or sheet of briquettable material from which the briquette of Figure 5 is produced,

Figure 7 is an enlarged view of a portion of the rolled material of Figure 6, and .

Figure 8 is a top elevation of the strip shown in Figure 6 from which the briquette of Figure 5 is produced.

Referring to Figure 1, the conditioning chamber is indicated at 10. It is elongated and has a mixing conveyor of the rotary paddle mixer type i I extending substantially throughout its length. The blades or paddles may be uniformly spaced or at certain portions more closely spaced to speed up the travel of the mixture at these points. A furnace 12 externally heats the chamber for substantially one-half its length. The chamber is thus divided into a heated area A and a tempering area B. It will be observed therefore that where the conveyor travels uniformly through the chamber the mixture will be exposed for substantially one-half the time to the heating area and during the remaining half of the time to the tempering area. The conveyor paddles may be arranged, however, to speed the agitation and travel of the mixture in the heating area to a greater extent than in the tempering area or vice versa. The combustible is fed to the heated area by a conveyor 13 discharging into a hopper 14 which delivers to a feeding conveyor 15. Likewise, the non-smoke producing binder preferably in dry form is fed from a binder hopper 16 by a feeding conveyor IT either (1) to the conveyor 15 and discharged with the combustible into the chamber 10, or (2) to a separate conveyor, hot shown, and delivered separately and simultaneously to the chamber 10 with the combustible. Where the binder is fed as a prepared paste, the feeding apparatus will simply be changed to accommodate the binder in this state.

In some cases, the binder mixture will comprise a major amount of the non-smoke producing binder and a small percentage of a waterproofing or other agent or supplemental binder when necessary. On the other hand, the waterproofing agent may be separately supplied from a tank 19 heated at 20 by means of a pipe 21 and delivered (1) to the chamber either at the entrance end simultaneously with the combustible and smokeless binder, or (2) the pipe 21 extends into and along the chamber and the binder is discharged into the mixture at any point, for example, at the beginning of the tempering area through a suitable outlet or spray 22. This sup plemental binder or waterproofing agent may be supplied with the coal or with the primary binder or separately introduced at any point in the chamber.

At the opposite end of the chamber the final 5 plasticized briquettable mass is delivered from the outlet 23 to the briquette press 24 and the formed briquettes removed by a suitable conveyor 25.

In Figure 2, the plasticized mass is first passed between rollers 26 and formed into a thin fran- 10 gible strip 27 of substantially Λ thickness, as shown in Figure 6, which strip easily breaks up and is collected in a feed hopper 28 and fed to the briquette press and formed into briquettes.

It, is to be observed (1) that the method is 15 continuous, (2) that the quantity of the mass under treatment is regulatable, (3) that the heat applied to the mass may be controlled, (4) that the speed of travel of a definite mass and its time cycle in the heating and tempering areas may 20 be regulated, and (5) that all operations for the production of a final conditioned and briquettable plastic mass of required temperature, moisture content and having the binder in optimum adhesive state are carried out as a single step in 25 the chamber 10.

We also provide means comprising a pipe 29, shown in dotted lines having outlets 30 for supplying moisture, as water or steam, at any point in the chamber as where the binder is supplied 30 in dry form and the quantity of moisture present in the combustible is insufficient to assure either proper spreading of the binder or its correct cooking and conditioning to a state of optimum adhesiveness, and also to insure a precise plas- 35 ticity in the final briquettable mass. This line 29 also represents a bank of steam pipes or coils for applying heat to the chamber and the outlets 30 may be used to inject dry steam into the ipixture for the purpose of heating the same. This 40 heating by means of the line 29 may be the sole heating means or supplemental to the furnace heating.

As frequently is the case, the combustible, such as coal screenings, especially anthracite culm, 45 will be wet and the moisture present is sometimes more than sufficient. In any event, the moisture may be regulated, and be present (1) in the combustible; (2) in the binder or a prepared paste; or both; or furnished (3) to the mixture in the chamber from a separate source, either as the sole moisture supply or added where moisture is already present to correct for any insufficiency.

The method is, therefore, applicable under a wide range of conditions and can be employed in various localities without restriction.

The important consideration is to form progressively a final plastic briquettable mass by a single step in which (a) the binder is thoroughly and uniformly mixed with the combustible and is cooked with the combustible to a state of exerting optimum adhesiveness, (b) wherein the moisture content is such that the binder will have optimum activity and the mass the required plasticity, and (c) the temperature of the mass is such that (1) it will dry rapidly and the binder will set quickly under these conditions of moisture content and optimum adhesiveness, i. e„ the briquette will be self-curing. This self-curing takes place within an economic time cycle and 70 the rapidity with which it is accomplished, will be understood when it is considered that the dry-.

ing of the briquette and the setting of the binder takes place within the time period of the normal operation of the briquette press since the bri- 75

2,017,402 quettes ejected from the press are finished ready for use.

The operation of the method as stated, is continuous, and the quantity treated in the chamber 5 10, the speed of travel, the agitation, and the heat applied are controlled in accordance with the particular combustible and binders or other ingredients employed. The travel of the mixture through the chamber whereby a progressive cook10 ing and conditioning is accomplished will usually be relatively slow, but, of course, may be speeded up as occasion permits. For efficient operation, a large quantity of the combustible mixture is usually under treatment in the cham15 ber, and this treatment will be regulated by the several means of control described. This flexibility of control is important because in. cases where the moisture of the coal screenings or culm is excessive more time will be required for 20 the elimination of moisture than in cases where the water or moisture is normal or sufficient. For example, a chamber having a five ton per hour capacity receiving coal screenings or culm of 5% moisture content is best operated with the 25 chamber filled to two-thirds capacity. In this manner, substantially two and one-half tons of mixture is under treatment and the , total time consumed in passing the mixture through the chamber is substantially thirty minutes. If the 30 moisture content of the coal screenings or culm should be 10%, the operation will be carried on with the chamber full or nearly full and the total time the mixture is exposed to treatment will be approximately forty minutes. Since the heat 35 applied to the chamber is capable of regulation, it is preferable to apply a greater amount of heat to the mixture when the coal screenings or culm contain excessive moisture. This is accomplished by simply increasing the tempera40 ture in the furnace under the chamber.

In this connection, while we have referred to a furnace positioned below the chamber 10 as the most convenient means of heating the chamber, additional heat may be supplied to the chamber 45 by means of steam pipes disposed in the chamber and if desired, dry steam may be injected into the mixture at the entrance end of the chamber or at any point therein during the travel of the mixture through the chamber. We men50 tion dry steam, but, of course, saturated or superheated steam may be injected into the mixture particularly in cases where added moisture is desired. The steam line 29 therefore is either or both a heating means, or a means for supplying 55 moisture to the mixture at any point during its travel in the chamber or at the entrance end of the chamber.

It is to be noted that the furnace under the conditioning chamber 10 extends about one-half 60 the length of the chamber and the invention comprises positively heating the coal and binder, for example, a starch binder, in the presence of moisture during substantially one-half of the total time the mixture is exposed to treatment 65 in the chamber iO. During the remainder of the treatment, the temperature of the mixture is lowered and tempered, but, as stated, the plastic mass discharged from the tempering area is sufficiently hot so that a self-curing action of the 70 briquette takes place. Any small percentage of excess moisture remaining in the briquette which is usually negligible, is readily and quickly evaporated and removed during the briquetting action and immediately thereafter.

it is to be observed that the operation of pre paring smokeless briquettes in accordance with this invention comprises two essential steps and is free from any drawbacks of conventional briquetting methods which now utilize from necessity (a) a preliminary heat treatment or drying 5 of the combustible, and (b) a subsequent heat treatment of the soggy and weakly adhesive briquette. That is to say, in the present invention, whether the coal be in a wet condition or in a dry condition is not material. The binder likewise 10 may be initially prepared as a paste, but is preferably presented to the combustible in dry or its normal condition, whether aqueous or non-aqueous. In any instance, where the moisture present is insufficient to properly cook the binder 15 and plasticize the mixture, provision is made for supplying an adequate amount of water or steam. Whereas, present conventional procedure is arduous, uncertain and expensive because the raw briquettable mass is soggy and the adhesive weak, 20 the operation of the present invention due to its simple control features marks a decided advance in briquetting practice because the briquettable mass is heat treated and precisely plasticized before briquetting. By control features, we mean 25 (1) that the quantity of the mixture under treatment may be regulated, (2) that the moisture content is reduced to the desired minimum either by raising or lowering the applied temperature or the period in which the mixture is subjected 30 to heating and tempering through regulation of the speed of the paddle conveyor, or both, and (3) the optimum adhesiveness of aqueous and non-aqueous binders is made available and the binders are concentrated to their most effective 35 state, and (4) the briquette is hot enough to be rapidly self-curing. These means of control are very simple and thoroughly effective, so that they may be easily operated to take care of particular types of combustibles and particular types 40 of binders, as well as the moisture or water content of the mixture, which may vary in different localities. Recognition of these principles of operation have followed careful research efforts and the discoveries have enabled the production 45 of substantially perfect briquettes by an economical method free from those obstacles which have tended to discourage the production of briquettes of the smokeless type.

The self-curing of the briquette is of vital im- 50 portance in the briquetting operation, primarily because it eliminates any subsequept heat treatment or air-drying of the briquette; which is both expensive and time consuming. Moreover, the briquettes, as ejected from the press are, as 55 stated, tough and firm, and practically dry so that they are finished and may be immediately handled and shipped, or stared, or consumed. That is, they are not squashy or fragile, but firm and integral. In further explanation of this self-cur- 60 ing action, it is to be understood that the briquettable mixture having the desired moisture content to assure the desired plasticity and adhesiveness of the binder, is supplied to the briquette machine from the tempering area of the 65 chamber 10 in a heated condition. The temperature, of course, will be controlled to accord with the particular combustible and binder employed. The heat in the mixture and the briquetting action serve to dissipate any remaining moisture 70 and to set the binder. Apparently, what takes place is that during the briquetting action, any objectionable moisture is exuded and immediately evaporated, the plastic mass being uniformly hot due to the thorough agitation and tempering 75

2,017,402 which it undergoes. Thus, the briquettes ejected from the press are substantially dry or possess a minimum of moisture. As to the latter, the hot briquette surfaces dry rapidly and apparently atδ tract, through capillary action, any moisture remaining in the interior of the briquettes which likewise is immediately evaporated.

The invention is applicable for the manufacture of briquettes using various of the following 10 comminuted combustible materials either alone or in combination:—?

Coal screenings of all types in ground condition.

Anthracite culm (which is usually in wetted 16 condition)

Bituminous coal

Anthracite coal

Lignite

Charcoal

Coke oven braize or coke braize

Petroleum coke

Low temperature char.

The moisture in coal screenings and other of the combustibles is usually very high, especially 26 when such coal screenings have been exposed to ground storage or come from a washery. Anthracite culm for instance, is always washed in order to lower the ash content.

This moisture content in the combustible is no 30 hindrance to the present invention but rather an advantage, since usually it is sufficient to form the required spreadable binder solution or dispersion and afford the desired cooking of the binder. ^w

In some cases, the coal screenings and other combustibles are too dry to carry on the process of cooking the binder, i. e. possess no moisture or have insufficient amount of moisture present. This deficiency is overcome by supplying satu40 rated steam or water into the mixture through the line 29 in the chamber 10. Of course, moisture may be supplied to the combustible or the binder or both before their introduction into the chamber, but this is not preferred.

The amount of moisture in the mixture in the ' conditioning chamber iO will always be in excess of which is to remain in the mixture when it is briquetted. The heat treating of the mixture will cause the excess moisture to be evaporated to a point where the mixture is plastic and the binder in its optimum state of adhesiveness for briquetting, producing strong and tough briquettes.

The primary binders employed are of the non55 smoke producing type as listed below, and this invention enables the use of a wide range of binders, i. e., those available in a particular locality, as well as binders and binder combinations novel to the briquetting art.

Organic and inorganic binders are used with success as are binders and bonding materials which are soluble in water or insoluble, or soluble at the start and ipsoluble after completion of the process:— ‘

Ground grain and glutinous materials Starcn and starch bearing substances Tubers such as potatoes and yams (preferably shredded or macerated)

Com

Wheat

Barley

Oats

Rye

Dextrine

Tapioca

Soy bean meal (preferably with one part sodium hydrate to ten parts meal) “Soy bean cake” “Linseed cake’”

Cellulosic materials

Clays

Bentonite

Lime

Cement and cement mixtures

Portland cement

A small percentage of calcium chloride may be io added to accelerate the hardening action of the ' cement in the briquette.

Magnesium oxychloride cement Sulphite liquor

Molasses and molasses slop;

By ground grain, we mean substantially all varieties of grain having starch or glutens. Such grain is preferably ground to a fineness that will practically eliminate the hulls. This fineness is 20 also important from the standpoint of obtaining efficient mixing with the carbonaceous and combustible -materials. We have developed by screen testing that in most cases best results are obtained if the finehess approaches that of flour, 25 although, if the ground grain is passed through a twenty mesh screen, it is satisfactory. For our purposes deteriorated grain is employed or flour, starch, dextrines, glutens, etc., which have deteriorated are still suitable as binders. 30

In connection with the use of glutinous, starch bearing and cellulosic materials as above recited, we find that these are preferably heated in the presence of water, i. e., cooked sb' as to be soft and plasticized and dissolved or dispersed in or- 35 der to bring out and make available their optimum adhesive principles and to attain efficient spreading action with maximum distribution and mixing of these principles with the combustible. Initially, however, due to the moisture or water 40 present, the binder lacks optimum adhesive properties. Therefore, after first obtaining the ultimate in spreading and distributing properties of these binders, 1. e., by their immediate mixing with the combustible in the chamber iO, the heat 45 treatment is continued until we progressively obtain the ultimate in cementing properties. This is reached when the starch or ground grain or other binder begins to stiffen for lack of moisture. This heat treatment can be controlled (1) by the 50 applied temperature and (2) by the speed of travel of the mixture through the chamber, i. e., through the heated area A and the non-heated tempering area B. The initial moisture or water content present in the ingredients of the mixture 55 fed to the chamber is therefore unimportant in view of these control features, which is of vital advantage. If sufficient or an excess of water or moisture be present, it will be reduced as the binder is conditioned, and in event of a deficiency, ⁶⁰moisture and/or water will be supplied in correct amount. As to the addition of water or moisture, this is usually and preferably applied initially to the mixture in the chamber at the entrance end,&lt;but can be preliminarily added to either ingredient or at any point during travel of the mixture through the chamber. Enough moisture is always left in the mixture to have the binder in its optimum state of adhesiveness and the mass of a briquettable plasticity and temperature to be self-curing. As heretofore stated, in connection with a starch containing binder, the solid combustible, the binder and water, are brought together under conditions to prevent premature 75

2,017,402 gelatinization of the starch. That is to say, initially the starch and water are not subjected to any temperatures such as would promote rapid evaporation of the water and hardening of the 5 binder such that it would not be spreadable and would become hard or charred and hence non-adhesive. On the contrary, the three members are brought together under conditions to promote complete spreading and thereafter the mixture 10 is continuously agitated to spread the binder and simultaneously the temperature of the mixture is progressively increased to assure proper removal of water and reduction of the starch to its adhesive and gelatinized state, i. e., the starch is 15 rendered adhesive and the mixture plastic so that it may be briquetted without the necessity of tak- ing the final plastic mass and giving it a drying treatment before introduction to the briquetting press. The tempering area into which the heat20 ed mixture is introduced continuously and agitated, assures that at the outlet to the briqueiting machine or other instrumentality, the briquettable mixture will have assumed a final briquettable state without need of additional treat25 ment and may be directly briquetted.

As regards the use of tubers such as potatoes and yams, these are valuable non-smoke producing binders which have heretofore not been practical because of the moisture which they con30 tain. Such tubers when shredded or macerated can be fed in the manner described either with the combustible or separately thereto in the chamber. As understood, the present invention is in no way affected by the moisture contained 35 in the potatoes or yams which is rapidly eliminated through the application of direct heat in the chamber iO. The mixture of combustible, whether it be wetted, partially wetted or in dry condition, and the macerated tubers are cooked 40 and conditioned and the binder spread and mixed with the combustible, and the moisture progressively evaporated to produce a properly plasticized briquettable mass. In connection with the use of tubers, secondary binders may be mixed 45 with the macerated potatoes or yams, with the combustible, or fed separately to the combustible mixture in the chamber. Again, in localities where secondary binders such as asphaltum and coal tar pitch, etc., are not readily obtainable, 50 they may be omitted if the briquettes are marketed in containers or under cover or in any manner where contact with water is prevented.

In connection with sulphite liquor and molasses and similar materials, these are sometimes quite ⁵⁵ thin and by reason of the progressive agitation and the cooking treatment, are reduced to the point where they have the required adhesiveness. In such cases the presence of moisture in the combustible is not objectionable since it Is rap⁶⁰ idly evaporated and, of course, it is not necessary to have moisture present with materials of this character.

As regards the use of clays and cement or cement mixtures, these are preferably fed dry ⁶⁵ to a wetted coal or combustible or moisture is supplied to the chamber 10 if the combustible is deficient. The moisture permits spreading and dispersion of such binders as well as condi₇₀ tions and concentrates them to the required state of adhesiveness. Sufficient moisture is permitted to remain in the hot plastic briquettable mass so that the cements and clays will set rapidly at the temperature of the mass.

The primary binders above mentioned are smokeless and are the principal means of agglomerating and cementing the particles into a strong solid form from which no dust or deterioration will result from handling and storage. They are moreover, susceptible to the cooking 5 and tempering action which takes place in the chamber 10, whereby (1) the binders are cooked and spread over and mixed with the combustible; (2) the binders are rendered to a state of optimum adhesiveness; (3) the moisture in the 10 mixture is reduced so that (a) the mass is plasticized to a briquettable plasticity and (b) the binders are in maximum active condition, and (4) the temperature of the mixture discharged from the chamber 10 is controlled so that with a 15 given binder and moisture content, the briquettes are immediately formed into finished articles, i. e., they are firm and strong when ejected from the press and are self-curing.

In some cases we utilize a secondary binder 20 preferably in amount only sufficient to exercise its particular function. For example, some briquettes wherein glutinous or starch bearing materials are used as the bonding agent required a waterproofing agent. Also, some briquettes are 25 enhanced by a coking of the binder. We employ secondary binders having one or both properties as listed below, and these are added (1) in a mixture with the combustible and primary binder, (2) with one or the other of these members, and 30 (3) separately and either at the entrance end of the chamber or any point therein, for example, at the beginning of the tempering area.

Asphaltum

Asphaltum oils 35

Residual matter from the distillation of crude oil

Coal tar

Coal tar pitch

Residual matter from the distillation of coal 40 Bunker “C” oils

Crude mineral and vegetable oils

Fatty acids of mineral and vegetable origin Distillates from by-product coke ovens which are suitable as binders. 45

Distillates from crude mineral and vegetable oils

Resins, gums and resinous material.

One or a mixture of the several secondary binders may be employed. As an example of a binder 50 having the property of imparting moisture resistance to the briquettes as well as having coking propensities, we prefer coal tar pitch. This compound derived from coking coal creates strong coking propensities. Thus, such a binder 55 used with a briquette of anthracite culm for example, tends to coke and strongly bind the particles of the briquette during combustion.

Because of the strong binding action exerted by the smokeless binders described, the amount of these secondary and usually smoke-forming binders need only be limited, by their function. That is, only sufficient secondary binder need be employed to render the briquettes impervious to g₃moisture. This is important since the briquettes remain for all practical purposes smokeless, by reason of the predominance of the non-smoke producing binders and their thoroughly effective binding action. Thus, a smokeless briquette is 70 obtained by the simple method already outlined and wherein the necessity for smoke producing binders or other smoke-forming ingredients is obviated.

As above stated, the secondary binder, for ex- 75

3,017,403 ample, Coal tar pitch, may be introduced into the chamber mixed with or separately, but at the same time as the primary binder, such as starch •or ground grain or the other binders mentioned 5 or at any time before the mixture is briquetted.

The varying constituents of the coal will determine when the secondary binder is to be introduced. Anthracite coal for example, requires different treatment from bituminous coal and this 10 is true with respect to certain of the other combustibles mentioned. It was found that when both binders were introduced simultaneously, good results were obtained with a certain carbonaceous material, whereas, a different combus15 tible would show better results wfien the starch or ground grain or other primary binder was first introduced and cooked with the coal before the secondary binder entered the, mixture. This secondary binder .as stated, is used only to make the 20 briquettes impervious to moisture and the quantity is held to a minimum for that purpose.

Examples

The following examples are representative of briquette compositions which are employed in accordance with the improved method for the manufacture of smokeless briquettes. It is to be observed that they meet the very exacting re30 quirements of having as the primary binder a non-smoke producing adhesive and that the secondary binder, wherever it is smoke forming, is present to a substantially negligible minimum. In the manufacture of the final briquettable 35 plastic mass, the materials are mixed and progressively cooked to bring out the optimum adhesive properties as well as reduce the moisture content to the required minimum. With some of the binders, as for example, the insoluble ones 40 such as clays, cement and cement mixtures, the cooking takes the form of dispersing the adhesive, and particularly of regulating the moisture present to such an amount as will assure rapid self-curing of the briquette and hardening of the 45 binder under the temperature conditions employed.

The ingredients of the mixture comprising the carbonaceous materials and binders are intro. duced into the chamber preferably at atmospher50 ic temperature and then given the required heating and conditioning treatment. In many cases, the moisture present in the combustible is sufficient to produce the desired solution, dispersion and cooking of the binder so that no excess mois55 ture is present. In this connection^ the important result obtained by the invention is the production of a plastic briquettable mass wherein the binder has been so cooked and concentrated that the briquettes delivered from the machine have the required strength and will withstand handling and loading. Stated briefly, the various binders employed are reduced by the heat treatment and the tempering action to a residue _β5 of a required strength whereby the briquettes ejected from the briquette press are finished.

With respect to the combustible employed, one of those above mentioned may be Used alone or two or more thereof combined. This is also true 70 with respect to the primary binders as well as the secondary binders. \

It will be observed that with several of the briquette compositions now to be described both the primary and secondary binders are non-smoke 75 producing. The method employed with the pres ent invention has enabled these binders to be employed and form a strong and tenacious briquette.

No. 1 ₆

Combustibles— Anthracite coal_____________ . Bituminous coal.__________:. Total weight—

Coke braize_______________ 1860 to 1940 lbs. io

Petroleum carbon, etc_______

Binders—

Ground grain.

Flour._________

Starch________

Dextrine—____

Tapioca—____

Glutens_______

Hydrocarbons.

Asphalt_______

Coal tar pitch.

Total weight— ¹⁵

100 to 40 lbs.

Total weight— ²⁰40 to 20 lbs.

This mixture is representative of a briquette wherein the primary binder is smokeless and the secondary binder is smoke producing but is pres25 ent in negligible percentage.

No. 2

Combustibles— 30 . Anthracite coal____________

Bituminous coal__________Total weight— , Coke braize________________ 1820 to 1940 lbs.

Petroleum carbon__________

Binders—

Ground grain---------------Flour------------------------Starch—.____________________ Total weight—

Dextrine_____________________ 100 to 40 lbs.

Glutens---------------------Tapioca_____„_______________

Portland cement—

Magnesium oxychloride cement.

Total weight— 80 to 20 lbs.

This briquette composition is an example of a briquette wherein both binders are non-smoke producing, and the secondary binder imparts moisture resistance.

No. 3

Combustibles— Anthracite coal. Bituminous coal. Coke braize—____

Petroleum coke..

Total weight— ⁵⁵1820 to 1920 lbs.

Binders— Ground grain.—-----------Flour___________—____\------Starch____________,________....

Dextrine:________________—.

Glutens__________---.________

Tapioca.._________,______,L____

Portland cement—

Magnesium oxychloride cement.

Total weight— 80 to 40 lbs.

Total weight— 60 to 20 lbs.

Asphalt______________________

Coal tar pitch_______________

Bunker “C” oils------------- Total weight—

Crude oils or the fatty acid 40 to 20 lbs. oils of vegetable or mineral origin_______—._______:____j

2,017,402

<td> No. 4 Combustibles— Anthracite coal-------------- Bituminous coal—---------- 5 Lignite_____________________ Coke braize---------------- Petroleum carbon----------- Binders— Soy bean meal with one part o ¹⁰ sodium hydrate to ten part of the soy bean meal------ “Linseed cake,” Asphalt-------------------- 15 Coal tar pitch------------- Bunker “C” oils—---------- Crude oils------------------ No. 5 Combustibles— ^M Anthracite coal------------- Bituminous coal----------— T.ienite -----------</td><td> T If f 1 s</td><td> No. 8 Combustibles— Anthracite coal--------------- . Bituminous coal-------------- atal weight— Lienite 60 to 1940 lbs. £_o^g_ke _______ Petroleum carbon—---------- Binders— _ , . ... Portland cement------------— WOtoloffis. ^Mmeⁿnt^iUm Potatoes---------------------- Yams______‘------------------ Total weight— Starch bearing tubers---------. 40 to 20 lbs. g Combustibles— Anthracite coal------,------- Bituminous coal—--------- Lignite______________________ Total weight— Coke braize------------------</td><td> Total weight— _ 1720 to 1900 lbs ® Total weight— 80 to 20 lbs. Total weight— 200 to 80 lbs. jg 20 Potal weight— L700 to 1880 lbs. '</td>

<td colspan="2"> Coke braize------------------ — Petroleum carbon------------- zo Binders— Portland cement----------.---- Magnesium oxychloride cement----------------------- 30 “Soy bean cake” with one part in ten of sodium hydrate----- “Linseed cake”—,------------- No. 6 35 Combustibles— Anthracite coal-------------- Bituminous coal----------—— Lignite----------------------- 40 Coke braize------------------ Petroleum carbon------------ Binders— Portland cement-------------- Magnesium oxychloride ce⁴⁵ ment-----------'----------- Soy bean meal or “soy bean cake” with one part in ten of sodium hydrate------------- 50 “Linseed cake”------------— Asphalt----------------------</td><td> Binders— Portland cement-----——----- Magnesium oxychloride cement— Potatoes______________________ 80 to 20 lbs. _yams________________________ Starch bearing tubers--------- Total weight— Asphalt—------------------- 100 to 40 lbs. Coal tar pitch---------------- Bunker “C” oils--------------- Crude oils or any of the fatty acid oils of vegetable or mineral origin-------------- Total weight— _N 1820 to 1920 lbs. Combustibles— Anthracite coal--------------- Bituminous coal-------------- :::::=: Petroleum carbon------—— Binders— --------------- Portland cement-------------- Magnesium oxychloride cement______________________</td><td> 25 Total weight— 60 to 20 lbs. Total weight— on 200 to 80 lbs. Total weight— « 40 to 20 lbs. 40 Total weight— 1780 to 1870 lbs 45 (Total weight— [140 to 90 lbs. 50 Total weight80 to 40 lbs.</td>

<td colspan="2"> Bunker “C” oils--------------- Crude oils or any of the fatty ⁵⁵ acid oils of vegetable or mineral origin-------------- No. 7 Combustibles—^{1 60} Anthracite coal--------------- Bituminous coal-------------- Lignite---------------------- Coke braize------------------ Petroleum carbon-------------- 65 Binders— Potatoes----------:---------— Yams---------------:—------ Starch bearing tubers--------- 70 Asphalt--------------------- Coal tar pitch——------- Bunker “C” oils-----------1— Crude oils or any of the fatty acid oils· of vegetable or 75 mineral origin-------------</td><td> Total weight— _Nn 40 to 20 lbs. Combustibles— ' Anthracite coal--------------- Bituminous coal-------------- Lignite______________________ Coke braize__________________ Petroleum carbon_____________ Total weight— _Blnders_ 1760 to 1900 lbs. ^B1jS^_s_____________________ Molasses slops--------------- Portland cement-------------- Magnesium oxychloride ce- 1 Total weight— ment---------------------- 1200 to 80 lbs. No. 12 Combustibles— Anthracite coal------------ Total weight— Bituminous coal------------- 40 to 20 lbs. Lignite—----------------- Coke braize----------------- Petroleum carbon------------</td><td> 55 Total weight— 1780 to 1870 lbs. 60 1 Total weight— J140 to 90 lbs. . 65 (Total weight— 80 to 40 lbs. 70 Total weight— 1780 to 1870 lbs. 75</td>

ΙΟ

2,017,402

Binders—

Molasses---------------------.1 Total weight—

Molasses slops—._____________J160 to 100 lbs.

Asphalt—.____________________ ⁵ Coal tar pitch________________

Bunker “C” oils---------------Total weight—

Crude oils or any of the fatty 60 to 30 lbs. acid oils of vegetable or mineral origin______________

No. 13

Combustibles—

Charcoal— 15

Total weight— 1200 to 1300 lbs.

Binders—

Ground grain________________

Starch—____________________

Dextrine---------------------Total weight— ²⁰ Flour------------------------140 to 80 lbs.

Gluten______________________

Tapioca_____________________

Water- 1 Total weight25 vva -1 660 to 620 lbs.

No. 14

Combustibles—

Charcoal.

Total weight— 1200 to 1300 lbs.

Binders—

Ground grain.

Starch_______

Dextrine_____

FIour_________

Gluten_______

Tapioca_______

Portland cement_____________

Magnesium oxychloride cement____________________

Total weight— 100 to 50 lbs.

Total weight— 60 to 30 lbs.

Water.

Total weight— J 640 to 620 lbs.

It is to be noted that the present invention will utilize satisfactorily coal screenings of various types and particularly coal screenings containing water or moisture which have heretofore not been available without the expense of pre50 liminary drying.

As regards the binders, any of the non-smoke producing primary or secondary binders may be used alone. This is particularly true with cement and cement mixtures which are sufficiently ad55 hesive, non-smbke producing, and render the briquette water-proof.

Both the primary and secondary binder may be non-smoke producing as desired, and the invention permits this flexibility of operation as 60 regards' the selection of binders and carbonaceous materials, whence it may be employed without limitation in accordance with operating conditions in particular localities.

In connection with the use of Portland cement 65 and cement mixtures, the briquettable mass is so heated and conditioned as to permit the cement to retain sufficient moisture to create additional hardness in the briquettes after they come from the press. In this manner the insolubility of the 70 briquette and its resistance to moisture is materially enhanced. A small percentage of calcium chloride or magnesium chloride may be added to accelerate the hardening action of the cement in the briquettes if desired.

In order to illustrate one representative method of carrying out the invention, anthracite culm screenings, a starch or ground grain binder and a secondary binder of coal tar pitch are employed. Where heretofore anthracite culm screenings have not been available unless first dried, with 5 the present invention, they may be fed in wetted condition directly to the chamber 10. The condition of wetness of the anthracite culm screenings from a washery or storage is ordinarily sufficient to promote the desired distribution and 10 cooking of the starch or ground grain binder. That is, there is enough moisture in the coal to make it unnecessary to add further moisture to the mixture. The coal screenings and the primary binder preferably in dry condition is fed 15 to the conveyer 15 and the mixture of combustible and coal are discharged into the entrance end of the chamber together. If desired, the secondary binder of coal tar pitch may be mixed with the primary binder or with the coal or fed 20 separately but simultaneously with the other ingredients to the entrance end of the chamber 10. The moisture present in the coal and the heat from the furnace 12 will immediately act to soften and plasticize the primary binder and this starch 25 bearing or glutinous material will thus be immediately dissolved and dispersed and distributed by reason of the rotating agitation promoted by the mixing conveyor II. As stated, the presence of moisture will soften and dissolve and disperse 30 the primary binder, but we find that the presence of heat and attendant cooking of the binder brings out the maximum adhesive properties of the binder so that its use is efficient. That is, in view of the fact that all of its adhesive prin- 35 ciples are made available the primary binder can be used economically. This cooking of the binder with simultaneous agitation assures that the treatment of the binder will be uniform. Of equal importance, the binder is treated in the 40 presence of the combustible so that the coal is likewise uniformly heated throughout its mass and the binder uniformly conditioned. The heat, of course, is more intense adjacent the entrance end of the chamber and decreases as 45 the mixture is conveyed towards the opposite end of the chamber. As the mixture is agitated and passed through the chamber, not only is the binder brought to its optimum active state, but equally important the reduction of 50 moisture which takes place relieves the initial mass of its soggy condition and the binder from its weak adhesive state producing a change wherein the binder stiffens and reaches a stage of maximum activity. As the heated mass is 55 conveyed through the chamber, it passes from the heated area A to this tempering area B. By reason of the rotary agitation and relatively slow movement of the mixture through the heated area, it is quite hot as it enters the tempering 60 area. There takes place a cooling, but in view of the high temperature of the mass, a considerable amount of the moisture, if any excess be ,present, is evaporated, and the binder further brought to its optimum condition. The mass as 65 it leaves the tempering chamber is hot enough to be self-curing, its moisture content assures the required briquettable plasticity and also the adhesive is in precise condition where it will exert its maximum adhesive effect. Further- 70 more, the plastic mass is at a. sufficiently elevated temperature so that the briquettes will be self-curing and that the binder will set within an economic time cycle. The Anal briquettes are hard and, tough and require no additional heat 75

2,017,402 treatment. The briquette comprises a major amount of non-smoke producing binder and a very small amount of smoke producing binder.

In order to illustrate another representative 5 method of carrying out the invention, mixture No. 2, above, will be utilized. Heretofore, anthracite culm screenings had to be preliminarily dried, whereas with the present invention they are fed in their wetted condition directly to the chamber 10 10. The presence of the moisture in the screenings permits a dry or relatively, dry binder to be employed and relieves the operation from the necessity of adding moisture. The primary binder, namely the starch or ground grain, may be 15 fed with the coal screenings or separately and simultaneously to the chamber 10. This primary binder is in dry or untreated. condition. The secondary binder, such as Portland cement may be mixed with either of the other ingredients or 20 fed separately and simultaneously therewith to the entrance end of the'chamber.

The moisture present in the coal screenings softens and disperses the binders and the complete solution and dispersion of all of the active 25 principles of. the primary binder is enhanced and rapidly accomplished by reason of the heating primarily, and the rotary agitation to which the mixture is subjected. The mixture moves slowly and progressively from the hottest end of the 30 chamber, during which time it is subjected to the rotary agitation whereby the combustible is uniformly heated and the binders uniformly cooked with required moisture removal. The temperature is controlled and the speed of agitation and 35 travel regulated so that the mixture from a weak and soggy mass, is changed into a substantially plastic condition and the binders stiffened to their optimum adhesive state by reason of the progressive reduction of moisture. The hot mass, 40 as it leaves the heated area, travels through and is given a rotary agitation in the tempering area where further reduction of moisture with concentration and conditioning of the binders takes place. The result is that the plastic mixture dis45 charged from: the tempering area is in Anal briquettable condition, both as regards the glutinous soluble binder and cementitious insoluble binder, both of which are properly cooked and concentrated. That is, the mass is sufficiently 50 plastic, contains the correct amount of moisture to render the binders quick setting and tenacious and the proper temperature, so that the briquettes ejected from the press are finished and are self-curing. This self-curing action may be 55 described as analogous to the baking of bread after the bread has been baked in the oven and removed therefrom and allowed to cool.

In this connection, where a cementitious or other insoluble binder is employed as the only 60 or primary binder, the heat treating, rotary mixing, cooking and tempering of the binder is progressively carried on as described.

With respect to binders of the order of coal tar pitch and other oily substances, these are 65 changed during the progressive heating and tempering treatment so that they are concentrated or rendered adhesive to the optimum degree. Where such binders are utilized in the presence of moisture, they are unaffected, in view of their 70 substantial insolubility.

It is to be understood that in many cases the moisture present in the coal is sufficient to accomplish the distribution and cooking of the binder. Moreover, in some cases, the binders of 75 non-aqueous character are flowable and spread able in the presence of heat and their slow and progressive cooking produces concentration of the binder and brings out its active adhesive principles.

While we have referred to a primary binder of 5 starch or glutinous material, readily dispersable in water, and an insoluble hydrocarbon binder such as coal tar pitch, it is to be understood that the process just described will be followed in the manufacture of briquettes of any of the composi- io tions mentioned.

The use of charcoal and a non-smoke producing binder such as starch or ground grain is made economically feasible by the present invention. Charcoal briquetting requires the introduction of 15 a very large percentage of moisture with starch or ground grain and the mixture is cooked and heat treated and tempered in accordance with this invention. Thereafter, it is briquetted.

The briquettes in the case of charcoal some- 20 times require further drying because of the initially large abount of moisture necessary and the limitations as to the heating temperature which may be employed, usually below 250° F. We find, however, by proceeding in accordance with this 25 invention that the briquettes delivered from the press are (1) firm and (2) the subsequent drying or heat treatment is considerably reduced. In present practice a soggy weak mixture is briquetted and then an expensive subsequent heat 30 treating of the fragile and squashy briquettes must be restorted to. Other of the primary and secondary binders are useful alone or in combination and with equally satisfactory results to produce charcoal briquettes. 35

We have also found that comminuted coal which has been purified by means of oils or other substances in accordance with well known treatments can be satisfactorily briquetted in accordance with this invention. In such cases, the 40 primary binders with or without secondary binders are mixed with the purified oil bearing coal, sufficient moisture being provided if necessary, and the mass heat treated and cooked and tempered to obtain a final briquettable, 45 plastic mixture. Any of the primary or second ary binders above mentioned may be utilized alone or in combination for forming a briquettable mixture from such purified oil bearing . comminuted coal. 50

We have referred herein to a furnace for heating the chamber as well as a supplemental heating means in the nature of the line 29 which may act as a radiator or convey dry steam into the mixture for heating purposes. In some cases, 55 we will rely upon the internal heating means alone and will not utilize the furnace. As heretofore stated, this internal heating means, in addition to heating the mixture, may also constitute a source of supply for moisture, if added 60 moisture is necessary.

We have referred herein to a condition of excess moisture which may sometimes occur and which is effectively remedied, whether in the binder or in the coal by the progressive heat 65 treating and tempering operation wherein the temperature applied and the speed of the mixture may be simply controlled. It is, however, to be understood that in the case of Coal screenings, the moisture content is often sufficient and 70 in the case of some of the binders, for example, tubers, the moisture present in the macerated yams or potatoes will likewise be substantially correct for maximum distribution and cooking of the binder. 75

2.017.402

In connection with the manufacture of charcoal briquettes, we have found that molasses and molasses slops constitute a very good binder. This particular binder can be substituted for one of the binders indicated in Examples 13 and 14 5 with very excellent results. The weight of molasses or molasses slops employed will be somewhere between one hundred and forty (140) to one hundred and fifty (150) pounds, and, in connection with Example 14, a suitable cement mix- 10 ture may be satisfactorily used.