US3140242A - Processes for producing carbonaceous materials from high oxygen coals - Google Patents

Description

July 7, 1964 Filed Aug. 3, 1960 ORK 140,242

FROM HIGH OXYGEN GOALS 2 Sheets-Sheet 1 FIGURE I FEED STOCK PRQCESS PRO D UCT STORAGE 8| COALS GROUND PARENT com. ANTRACITE THRU LIGNITE GR'NDING CATALYZING CATALYZED, DRY

STAGE NON AGGLOMERATING COAL CAR BONIZING CHAR STAGE VAPORS LIQUOR I CALClNlNG I STAGE CALCINATE TAR PITCH COOLING 55555615535 IWHEN NECESSARY: l

BLENDING FORMING GREEN SHAPES BRIQUETTES, EXTRUSIONS,ETC.

CUR|NG CURED SHAPES GAS C0 Kl NG JINVENTORS 05/4 Wok/f SHAPES FOBBFTZJOSEP/l BY JOHN/[BLAKE A TOANEYS' July 7, 1964 K ETAL 3,140,242

J. PROCESSES FOR PRODUCING CARBONACEOUS MATERIALS FROM HIGH OXYGEN GOALS Filed Aug. 5, 1960 2 Sheets-Sheet 2 N WWW United States Patent 3,140,242 PROCESSES FOR PRODUCING CARBONACEOUS MATERIALS FROM HIGH OXYGEN COALS Josiah Work, New Canaan, Conn., Robert T. Joseph, Richboro, Pa., and John H. Blake, Boulder, Colo., assignors to FMC Corporation, a corporation of Delaware Filed Aug. 3, 1960, Ser. No. 47,219 12 Claims. (Cl. 202-26) This invention relates to processes for producing physically strong, carbonaceous materials from coal. This application is a continuation in part of our co-pending application, Serial No. 821,137, filed June 18, 1959.

In our co-pending application is disclosed a process of producing physically strong carbonaceous materials from coals of any rank involving the following stages:

(1) The coal, if not already finely divided, is ground, for example, in a hammer mill, to a particle size small enough to be readily fluidized.

(2) These ground coal particles are pre-treated (catalyzed) in an environment of such characteristics that as the parent coal passes into and through the succeeding carbonizing stage a reduction in the hydrocarbonaceous volatile content and a polymerization of the remaining hydrocarbonaceous matter of the coal takes place and this Without destroying the original physical structure of the coal. This effect is presumed to involve the formation of catalysts of peroxide or hydroperoxide nature which are formed from a portion of the contained oxygen in the parent coal and/or from oxygen derived from the steam and/or air atmosphere in which this step is carried out.

This step must be carried out within a certain temperature range which varies from coal to coal, which is dependent, in part at least, on the time the parent coal is subjected to such temperatures, and which is limited by the distinguishable phenomena hereinafter set forth. The upper temperature limit, regardless of time, is that temperature above which the distilling vapors form tar when condensed. The lower temperature limit is that temperature at which contained moisture is evolved from the parent coals.

The residence times between these temperature limits necessary to accomplish this catalyzing effect depends on the processing treatment employed, the temperature within the limits stated and the rank of coal being processed.

Two further but important secondary effects of this stage, incidental to the primary purpose of catalyst formation, are:

a. The moisture content of the parent coal is reduced to limits found necessary for proper operation of the carbonizing stage, usually to 2% or less;

b. Where such exist, the coking and caking tendencies of the parent coals are destroyed by a small addition and/ or recombination of oxygen, derived from the parent coal or the atmosphere in which this stage is conducted, to form carboxylic groups as are found in humic acids.

These catalyzed coal particles are pyrophoric and should be handled in transport by procedures that will prevent undesirable oxidation.

This stage, which results primarily in effective catalyzing of the coal, is hereinafter and in FIGURE 1, re-

"ice

ferred to as the Catalyzing Stage. The products are referred to as Catalyzed Coal.

(3) The aforementioned catalyzed coal particles are subjected to further heating at rates and residence times, hereinafter set forth, to produce the desired density and reactivity characteristics in the calcinate product, i.e., that resulting from the subsequent stage.

The purpose of this 3rd stage is to carry on that type of polymerization which is promoted and directed by the catalysts (presumed to be formed in the catalyzing stage) in such a manner that a substantial portion of the parent coal constituents are retained in a form of the parent coal structure while, at the same time, an amount of these constituents (predicated on the predetermined environment of this stage) is evolved as vapors which may be condensed to form tars and gases for use in subsequent demands of the process. This stage effects a reduction in what is conventionally called the volatile combustible matter (VCM) in the parent coal.

The necessary heating rates and residence times may be achieved by introducing the catalyzed coal into a fluid bed reactor where the temperature rise is effected practically instantaneously, and Where the residence time of the catalyzed coal in this environment is controlled by the desired physical and chemical properties of the product. Within the limits hereinafter set forth, longer residence times, for a given temperature, produce higher densities but lower reactivities. Higher temperatures for a given, but shorter, residence time produces higher reactivities but lower densities. The properties imparted to the product char from this stage bear on and reflect directly in the products from the succeeding stages.

The heat for this stage is best obtained from combustion of such a portion of the catalyzed coal particles as is needed to supply the heat demands of the reaction, and control of this combustion is effected by admitting only that amount of oxygen (preferably as air) as will contain this prescribed level of combustion.

These car particles are pyrophoric and should be handled in transport by procedures that will prevent undesirable oxidation.

Hereinafter and in FIGURE 1, this stage is referred to as a carbonizing Stage and the solid product from this stage is referred to as Char.

(3a) The condensed, recovered tar vapors from the carbonizing stage are treated to produce a binder suitable for subsequent blending with the calcined char. This treatment consists of air or steam blowing. These tars, which have been drained of free water, are held at temperatures above the condensation point of steam but below that level where the passage of gases (air or steam) through the tar mass will cause distillation of light ends in excess of 5% by weight of the dry tar being so treated. This treatment is continued until a suitable viscosity increase is obtained, as hereinafter disclosed.

When binders derived from other sources are used, this treatment may or may not be employed.

(4) The char is subjected, preferably immediately, to further heating to reduce the remaining volatile content in the char to a 3% maximum. This, when effected in a fluidized bed with combustion of a portion of the char to provide the desired temperature, must be done in an atmosphere containing no more of such active gases as will produce the heat and no more carbon dioxide than will be produced by the combuston of that part of the char particles necessary to supply the heat demanded by this reaction.

These calcined particles are pyrophoric and should be handled in transport by procedures that will prevent undesirable oxidation.

Hereinafter and in FIGURE 1, this stage is referred to as the Calcining Stage and the product from this stage is referred to as Hot Calcinate.

(5) The hot calcinate is immediately and rapidly cooled to a temperature at which subsequent blending with the binder is effected, or to below 400 F., or to the temperature at which the calcinate is to be used when the calcinate is to be utilized as such. If used at a lower temperature, such cooling may be effected by introducing the hot calcinate into a fluid bed maintained at the temperature to which the calcinate is to be cooled, or accomplishing this stepwise by use of two or more fluid beds if heat economy so dictates. The effect of such cooling is to reduce loss of product by oxidation upon contact with air and, at the same time, to maintain the structure of carbon surface by preventing this oxidation.

Hereinafter and in FIGURE 1, this stage is referred to as the Cooling Stage, and the product from this stage is referred to as the Calcinate.

The chemically reactive carbonaceous material or calcinate thus produced may be utilized as such, for example, as raw material for water gas or other gas reactions in the place of coal or coke, or for effecting the reduction of ores as in sintered iron processes. It is remarkably strong, abrasive-resistant, homogeneous, of high bulk density, and exceptionally uniform in reactions with carbon dioxide, steam and oxygen.

These calcined particles are pyrophoric and should be handled in transport by procedures that will prevent undesirable oxidation.

(6) The calcinate is mixed with a binder (preferably the tar produced in carbonizing the parent coal after this tar has been treated by heat and air-blown to a prescribed softening point hereinafter disclosed) in such a manner that all the calcinate particles are surface-coated with the binder, a minimum of absorption occurs, and the calcinate and binder are so intermingled that subsequent processing causes co-polymerization of the binder and calcinate. This reaction is exothermic; the temperature of blending or mixing should be maintained at not more than 30 to 60 F. above the ASTM softening point of the binder used.

This stage, which effects the blending of binder and calcinate, is hereinafter and in FIGURE 1 referred to as the Blending Stage and the product is referred to as the Blended Material.

(7) The blended material is subjected to a compacting operation to form any shape demanded (as by briquetting, extrusion or any similar process) wherein the applied pressure on the blended mass is of such magnitude that the shape, when freed from the mold or die, will retain the form and be capable of withstanding abuse and handling at normal and elevated temperatures.

This product is pyrophoric and unstable and consequently should not be stored.

Hereinafter and in FIGURE 1, this stage is referred to as the Green Shapes (briquettes, extrusions, etc.).

(8) The green shapes from the forming stage are subjected to further processing by heating in an oxygencontaining atmosphere until co-polymerization of the binder and calcinate have been completed. In this stage the residence time and temperature are interrelated. This curing can be accomplished at room temperature in a matter of days, or at elevated temperatures, hereinafter given, in a matter of 60 to 180. minutes. Longer times at elevated temperatures affect the strength adversely. Accelerators can be used to reduce the time.

The minimum quantity of oxygen required in the curing atmosphere is 2.5% by volume; more can be used, if

desired, up to a maximum of 21% under the conditions hereinafter set forth.

The purpose of this curing stage is to promote maximum polymerization, presumably by peroxide or hydroperoxide catalyzation, between the binder and calcinate and thereby prevent formation of coke from the binder alone. This co-polymerization apparently acts to decrease the vapor pressure of the binder-calcinate system to such a level that, in the subsequent stage, coke is formed from the copolymers preferentially to distillation of the high vapor pressure components of the original binder.

This product is pyrophoric.

Hereinafter and in FIGURE 1, this stage is referred to as the Curing Stage and the product from this stage is referred to as Cured Shapes (briquettes, extrusions, etc.).

(9) These cured shapes are heated to reduce the volatile content, increase the strength, adjust the reactivity and produce the massive carbonaceous material final product. This is best accomplished by coking in an atmosphere substantially free of such reactive gases as carbon dioxide (which will react with the carbon of the massive forms to produce carbon monoxide and reduce yield), oxygen (which will react with the massive shapes to produce carbon monoxide and reduce the yield), and steam (which will react with the carbon of the massive shapes to produce hydrogen and carbon monoxide and reduce the yield).

A secondary detrimental effect of such side reactions is the partial consumption of individual shapes causing undesirable non-uniformity of size and surface.

This treatment must take place at a temperature sufficient to reduce the volatile combustible content of the final product to 3.0% or less.

The time necessary to accomplish these aforementioned ends is dependent on the temperature and is the time necessary for the coking reaction to reach that stage of completion at which the coke shapes have the desired strength.

The heat for this reaction is preferably supplied by direct contact with hot inert gases (for example, carbon monoxide or hydrocarbon gases produced in earlier stages) as in a shaft or on a moving grate. However, any other means of raising these cured shapes to the temperatures dictated by the specifications for the final product may be used. Such means may be direct or indirect, as by gas contact or by radiation from externally heated Walls, or by direct radiation sources.

The shapes, after having been subjected to the hightemperature treatment, must be cooled, preferably but not necessarily in the same apparatus, but in any case in an atmosphere free from reactive gases, as previously described, to such a temperature that harmful and yieldconsuming reactions with reactive gases do not take place.

Hereinafter and in FIGURE 1, this stage is referred to as the Coking Stage" and the product from this stage is referred to as Coke Shapes (briquettes, extrusions, etc.).

These shapes are exceptionally uniform in that the product, from boundary to boundary, is a homogeneous entity, as indicated visually by optical microscopy and chemically by the uniform, homogeneous consumption of the shape from all dimensions in any reactive medium. Those shapes have a high strength (denoted by resistance to compressive pressures on a 1%" diameter x /4" high cylindrical form) of at least 3000 pounds, a high bull; density, exceptional resistance to abrasion, and unusually high surface area for such high strength.

As disclosed in our co-pending application, the pretreatment elfected in the Catalyzing Stage is best accomplished in an atmosphere containing oxygen, the concentration of which varies inversely with the oxygen concentration of the coal being so treated in the Catalyzing Stage. The practical range of oxygen concentration is l%20% by volume in the entering fluidizing medium, dependent upon the rank of the coal. For low rank, noncoking coals, a volume of oxygen at or near the lower limit of this range is employed, e.g., from 1% to 8% by volume; for coking coals, a volume of oxygen in the upper part of this range is used, e.g., from 8% to 20% by volume.

The present invention is directed to a species of the generic invention disclosed and claimed in our co-pending application which species involves the treatment of high oxygen coals, i.e., coals containing at least about oxygen on a moisture and ash-free weight basis, hereinafter referred to as MAF. We have found that in the treatment of coals containing at least about 15% oxygen MAF, excellent products are obtained substantially the same in chemical and physical properties as those obtained employing added oxygen in the Catalyzing Stage as disclosed in our aforesaid co-pending application and this without the addition of oxygen as air or oxygen-enriched air to the atmosphere in which the Catalyzing Stage is conducted. Most available coals having such high oxygen content contain from about 15% to about 25% oxygen MAP; a few such high oxygen content coals contain 13% or 14% oxygen MAF. It will be understood that the expression coals containing about 15 oxygen includes all such coals. Moreover, in the treatment of such high oxygen coals, without such added oxygen introduced into the Catalyzing Stage, an improvement in the tar recovery during the subsequent carbonization stage is effected, i.e., a higher yield of tar can be obtained, if desired. Furthermore, the practice of the process is simplifled in that it is not necessary to employ measuring, control, and mixing equipment which is required when oxygen is introduced into the Catalyzing Stage in order to maintain a homogeneous atmosphere in the Catalyzing Stage. Why coals containing at least about 15% oxygen MAF can be processed in this manner, i.e., without the introduction of oxygen as air or oxygen-enriched air into the fluidizing gas employed in the Catalyzing Stage and still obtain the novel carbonaceous products, having the properties hereinafter set forth, is not fully understood. One probable explanation is that high oxygen coals which, geologically speaking, are relatively young coals, contain the oxygen in molecules (believed to the chiefly carboxylic in nature) of a character such that relatively weak bonding occurs between the oxygen and the hydrogen atoms in the same molecules and such molecules are relatively weakly bonded to each other. Hence, when the coal is subjected to treatment in the Catalyzing Stage at temperatures employed therein, namely, 250-500 F. these weak bonds break and release oxygen in an active state. This active oxygen catalyzes the attack on the coal matrix which attack is presumed to involve the formation of catalysts of a peroxide or hydrope'roxide nature formed from a portion of the oxygen thus liberated and/ or from a portion of the oxygen in the coal and/or from oxygen derived from the steam atmosphere in which this step is carried out; steam is invariably present, being introduced as such or formed from the moisture present in the coal. Whatever the explanation, the fact remains that in the treatment of high oxygen coals in the Catalyzing Stage, with no added oxygen, the ground coal particles are pretreated (catalyzed) and thus conditioned so that as the coal, particles pass into and through the succeeding carbonizing stage, a reduction in the hydrocarbonaceous volatile content and a polymerization of the remaining hydrocarbonaceous matter of the coal takes place without destroying the original physical structure of the coal.

The preferred conditions, generally applicable to the treatment of a high oxygen content coals will now be described with particular reference to the drawings, in which FIGURE 1 shows, for purposes of exemplification and to facilitate a better understanding of this invention, a box diagram of the sequence of stages of the process resulting in compressed coke shapes; and FIGURE 2 is a flow sheet showing a preferred arrangement of equipment for carrying out the process.

THE GRINDING STAGE In the practice of this invention, the coal, if not already of the required finely divided size, may be ground by any standard grinding and sizing technique to produce a natural distribution particle size, substantially all of which passes a No. 8 mesh screen and at least of which is retained on a No. 325 mesh screen and with a minimum quantity of fines of a size which would escape from the cyclone of the fluidizing bed reactors. This is readily accomplished by grinding in a hammer mill.

THE CATALYZING STAGE These finely ground parent coal particles are first subjected to pre-treatment, desirably in a fluidized bed, but alternatively in a dispersed phase, to promote, presumably, the formation of peroxide and hydroperoxide catalysts. This is accomplished in an entering fluidizing atmospherbe free of oxygen.

In this catalyzation of these coals and lignites, the fluid bed is normally maintained at a temperature of 250 F. to 500 F. The maximum of the range is that point in temperature at which hydrocarbon vapors, the tar precursors, begin to be evolved. The lower limit is that temperature necessary to reduce the moisture content to 2% or less, or, in the case of coal with less than 2% moisture, that temperature at which some of the oxygen contained in coal can be liberated to the fluidizing medium of this stage.

In carrying out this catalyzing, the parent coal may be introduced into a cold fluid bed and subjected to a gradual rise in temperature to the range indicated. Preferably, the parent coal is introduced continuously into a fluid bed maintained at the desired temperature, wherein the heating rate will be of shock or instantaneous magnitude for 1 second or less.

When heating the coal particles under fluidizing conditions, the coal particles should remain in the fluid bed for an average residence time of at least 5 minutes, and preferably from 5 minutes to 3 hours. This catalyzing may be accomplished in times as low as 10 minutes, or as high as 180 minutes, without the occurrence of deleterious effects on the final product. The temperature of catalyzation, with the ranges given, bears an inverse relationship to the residence time. In catalyzation of these coals at temperatures in the lower portion of the range of 250 F. to 300 F., the times should be in the upper portion of the residence range. On the other hand, when operating at the higher temperatures, near 500 F., the residence time should be in the lower portion of this time range.

The fluidizing medium, desirably steam or oxygen-free flue gas is introduced at a pressure of from 2 to 30 p.s.i.g. The fluidizing medium is introduced at a velocity to give the desired boiling bed conditions, e.g., from about 0.5 to 2 feet per second superficial velocity.

Heating of the finely divided coal particles in the fluidized bed may be effected by sensible heat introduced in the fluidizing medium, or by indirect heat exchange.

In lieu of effecting catalyzation of the coal in a fluidized bed, the finely divided coal particles may be subjected to heating in a dispersed phase, i.e., dispersed in a suitable gaseous medium (e.g., oxygen free flue gas, nitrogen, or carbon dioxide within the limits heretofore prescribed) of suificient velocity to maintain the particles in the dispersed phase rather than in the dense phase, as in a fluidized bed. Utilizing dispersed-phase heating, these coals are heated to a temperature of 350- 750 F. for about 3 seconds.

Catalyzation, as hereinabove described:

(1) Conditions the parent coal so that in further processing in the succeeding stages, a controlled amount of polymerization occurs which effectively increases the strength and thickness of the pore walls while permitting a predetermined amount of the coal constituents to evolve as gas and vapors, which vapors are subsequently condensed to tar to fill the demands of the total process;

(2) Effects the removal of contained moisture when hydrous coals are treated.

These effects are accomplished without sacrifice of the density-of-structure characteristic of the parent coal.

THE CARBONIZING STAGE Carbonization is carried out by subjecting the catalyzed coal particles to a further heat-treatment in a fluidized bed where the heat requirements are supplied, preferably, by the oxidation of a limited amount of the catalyzed coal or of the hydrocarbon vapors derived therefrom. This oxidation is controlled by the admission of only that amount of oxygen necessary to produce the desired temperature level. This oxygen is admitted to the bed in the form of air as a component of the fluidizing medium, the remainder of which may be steam, nitrogen, flue gas, carbon dioxide, carbon monoxide, or any gas which is not reactive with the catalyzed coal in this stage. Alternatively, heat may be supplied externally by use of heat exchangers.

In this stage the catalyzed coal particles may be heated under conditions:

a. So controlled as to produce a char having the desired optimum properties;

b. So controlled as to produce only that amount of tar consistent with the quantity of binder required for blend specifications.

Optimum conditions of the carbonizing stage will vary from coal to coal and may be determined for each coal processed by prior laboratory evaluation in bench-scale apparatus.

Temperature and residence time are critical. The lower limit of temperature is that temperature at which the activated coal begins to evolve tar forming vapors in quantity and this temperature is the same as the upper limit of the catalyzing stage for any given coal, i.e., approximately 500 F.

The upper limit of temperature is that temperature above which the expanding coal particles form cracks, fissures and bubbles to such an extent that retraction to the density-of-structure of the original coal particle can not occur. This upper temperature limit is approximately 11501200 F. In general, the higher the temperature of carbonization (within the lower and upper limits), the greater the quantity of tar produced.

The fiuidizing gas should enter the bed at a temperature not much below the temperature of the fluidized bed and not more than 20 F. above this temperature; if this fiuidizing medium is introduced at a much lower temperature than the bed, more of the catalyzed coal and hydrocarbon Vapors will have to be burned in order to supply the heat necessary to raise the fluidizing medium to bed temperature, thereby reducing product yields. If the fluidizing gases enter the bed at a temperature of more than 20 F. above the temperature of the bed, weak nonuniform char results.

The fluidizing medium is introduced at such superficial velocities as will effect the desired fluidization pattern, usually 0.5 to 2 feet per second and, desirably, at pressures consistent with the smooth operation of the whole process, e.g., 2 to 30 p.s.i.g., preferably about 5 p.s.i.g.

The material in the bed is maintained at the aforementioned bed temperature for to 60 minutes. The resideuce time at this point is a source of control of the chemical reactivity and other characteristics of the final calcinate or massive shape and is determined by the specification set for the final calcinate or massive shape derived from the calcinate.

The carbonization may be carried out as a continuation of a batch-operated catalyzing step wherein, particles being catalyzed having been held at the desired temperature for the specified residence time, the temperature of the bed is raised as rapidly as the reaction of the oxygen content of the fluidizing medium with the bed will achieve carbonization temperatures. Or, preferably, this carbonization may be carried out by continuously feeding the catalyzed coal from the catalyzing stage directly into a fluidized bed maintained at the carbonizing temperatures as previously described. In this case the heat transfer rates within the bed are of such a magnitude as to effect instantaneous shock heating of the particles.

Unless the parent coal particles have been treated as prescribed in the catalyzing stage, irreversible expansion of the particles results from non-elastic rupture and explosion of the pore walls. The resulting chars, while useful as boiler fuels, cannot be further processed to produce the calcinate or massive shapes that will be competitive with or su erior to the cokes from by-product, beehive or similar ovens.

It is only by following the sequence of stages above described that high-density, high-strength calcinate particles (which may be subsequently formed into homogeneous stable shapes) result.

RECOVERY AND PREPARATION OF THE TARS That controlled portion of the coal constituents which is evolved as gas and vapor from the coal particles may be processed to produce tars and gas for use in the process. The vapors may be cooled by direct contact with a recycling water spray to such a temperature that about of the vapors are condensed to tar. The uncondensed 20% goes forward through conventional heat exchangers and is cooled to about 40 F. above the cooling medium temperature which circulates indirectly over the heat exchange surfaces, at which temperature some further condensation takes place. The two condensates are combined to give the total wet tar which is allowed to settle, and the water is decanted to leave a decanted tar of about 4%6% moisture content.

Alternatively, the gas and vapor stream may be cooled by direct spray, or, conventionally, through indirect heat exchangers to such temperatures as will totally condense the tar producers to tar and allow only the normally non-condensable gases, such as methane, etc., to leave the heat exchangers. This results in a total condensate, not separate fractions. This total condensate is then decanted in the manner heretofore described.

Blowing the decanted tars so formed simultaneously dehydrates the tar to a water content of 0.5% and increases the tar viscosity to the desired softening point. A softening point Within the range of to 225 F., preferably to F. (ASTM Ring and Ball), is satisfactory for use as the binder.

This blowing is accomplished by the injection of air (steam may be used but is not as effective as air) through a suitable sparger into the decanter tar. This tar is maintained at a temperature above the condensation temperature of the steam, but below that point at which distillation of the tar light ends exceeds approximately 5%. The retained light ends are converted to binder of proper viscosity during the blowing treatment.

This viscosity increase may be accomplished by incorporating catalysts into the tar after dehydration. Suitable catalysts are organic peroxides, such as benzoyl peroxide, inorganic catalysts such as sulfuric acid, boron trifluoride or its complexes, aluminum chloride, etc. The useable catalyst concentration may vary from 0.1% to 2% depending on the tar, the catalyst and the viscosity range desired.

THE CALCINING STAGE The char particles from the carbonization stage are further heated to reduce the amount of volatile combustible matter remaining in the end product to below 3%. Desirably, this calcination is achieved in a fluid bed operating at that minimum temperature necessary to achieve this reduction, i.e., from about 1400 to 1500 F., and

for a residence time of from about 7 minutes to about 60 minutes. Higher temperatures may, however, be used but not exceeding about 1800 F. At an operating range of l500 to 1800 F. residence times in excess of 10 minutes effect a reduction in the chemical reactivity of the calcined product proportional to the length of the residence time in excess of 10 minutes. A secondary effect of this calcining is to increase the physical strength of the calcinate.

The residence times of the char in this stage are dictated by the specification of the final product and are more or less dependent on the operating temperature. At minimum temperature, suflicient residence time toreduce the volatile combustible matter to 3% is required. Practically, this limit is 10 minutes at about l400 to 1500 F. and should not be less than 7 minutes even at 1800 F.

The fluidizing atmosphere necessary in this stage should be free of reactive gases such as carbon dioxide or steam. Oxygen can be tolerated only in such an amount as is demanded by that oxidation rate of the char necessary to supply the heat demands of this stage. This oxygen is most practically obtained from air introduced as part of the otherwise chemically inert fluidizing medium, and the concentration of air for this purpose in these entering gases should not exceed 70%.

The remaining components of the fluidizing medium may be carbon monoxide, hydrogen, nitrogen and flue gas in which carbon dioxide and water have been reduced to carbon monoxide and hydrogen by previously passing the flue gas over a bed of hot carbon, or otherwise.

This fluidizing medium should be introduced at such pressures as are consistent with smooth operation of the fluidization process; a range from to 30 p.s.i.g., preferably about 2 p.s.i.g., is satisfactory. The velocity of this medium should be consistent with a proper fluidizing pattern, or the same as in the carbonization stage, e.g., 0.5 to 2 ft. per second.

It is advantageous to introduce the fluidizing medium at about the operating temperature of the bed. Lower than bed temperatures will demand increased oxidation of the char, with resulting deleterious effect of water vapor and carbon dioxide on the final product.

The heating may be accomplished as a continuation of the catalyzing and carbonizing stages, in the same batch-operating fluidized bed reactor, by raising the temperature of the bed to the desired calcining range, and holding the bed at that range until calcination has been completed. Or, preferably, the hot char may be introduced continuously and directly to a fluidized bed operating at the specified calcining temperature. In this case, the rate of heat transfer in the fluid bed is of such magnitude as to effect shock or instantaneous heating of the char to calcining temperature.

Unless the parent coal has been treated as prescribed in the catalyzation and carbonization stages, this shock heating will shatter the particles, producing extremely low apparent density, highly exploded fines. Such particles give evidence that the structure, density and fracture of the parent coal has been completely, adversely and permanently altered.

The calcinate produced by observing the conditions hereinabove described has the essential structure and apparent density of the parent coal particles.

THE COOLING STAGE The calcinate must be cooled rapidly and immediately to prevent loss of reactivity. This cooling, desirably, is effected in one or more fluidized beds, preferably two, in which the fluidizing medium also serves as the cooling medium and in which the heat transfer rate is of such magnitude as to effect instantaneous cooling. Suitable cooling media are flue gas, nitrogen, or carbon monoxide introduced at a temperature to effect the desired cooling and at a velocity to effect the desired fluidization. The

velocity may be substantially the same as that employed during the carbonization or calcination treatments. Cooling atmospheres containing appreciable amounts of oxygen, water vapor or carbon dioxide should be avoided because, in View of the highly reactive nature of the calcined char, such atmospheres may result in deleterious effects on the calcinate.

Where the calcinate is employed in producing massive shapes, it is cooled to a temperature approximately 30 to 60 F, preferably about 50 F. above the softening point (previously described) of the bituminous binder employed in the forming operation and used without appreciable time delay or exposure to air.

When producing calcinates for use as such, the calcinate must be cooled to approximately room temperature for storage or transport unless immediately used in hightemperature applications. This calcinate is pyrophoric; hence, if stored, it should be stored in a non-oxidizing atmosphere so that it will not catch fire.

THE BLENDING STAGE In order to produce massive shapes such as briquettes, extrusions, castings, etc., the highly reactive calcinate must be cooled to the proper temperature, 30 to 60 F. above the ASTM Ring and Ball softening point (100 to 225 F.) of the binder employed.

At this point the calcinate is mixed with the prepared binder, which is introduced at the proper mixing temperature, as heretofore specified, in proportions of from 75 calcinate to 25 %l()% binder. The percentages are based on the weight of the total mix.

These limits are critical, not only from the standpoint of co-polymerization and the production of final massive shapes of desired strength, but also from the standpoint that the green shapes must stand mechanical handling. Below the lower limits of this range of ratio of binder to calcinate, the green shapes Will tend to fall apart as a dry mix. Above the upper limits of this range, the green shapes will soften, sag and agglomerate during curing, with attendant losses and process difficulties.

The optimum ratio for dry calcinate to binder is determined by laboratory tests to give the strongest product consistent with high yields. If too much binder is used, the unneeded portion will distill out; if too little is used, the shapes will disintegrate in curing and coking, with attendant high losses due to the production of fines.

It is advantageous to complete blending in the time it takes to actually coat the calcinate particles with a uniform layer of binder; the time during which the mixing or blending is effected, is not critical.

Preferred binders are coal tar pitch or pitches produced by the condensation of tars from the gases evolved during the carbonization and subsequent dehydration and oxidation of the resultant tar to produce pitches having a softening point of from to 225 F. (ASTM Ring and Ball as described). High-temperature or low-temperature coal tar pitches are satisfactory, also.

When mechanical pressure is used to form the shapes, i.e., extrusion or briquetting, from this mixture of calcinate and binder, pressure in excess of 5,000 pounds per square inch is desirable. Below compacting pressures of this magnitude, the shapes will be sandy and tend to fall apart. Below this compacting pressure the shapes will, on final processing, not meet the requirement for physical strength. The maximum pressure usable and desirable depends on the size of the shapes and the type of equipment used. The higher the pressure, generally speaking, the greater the crushing strength of the final coked shapes.

Forming to shapes can be carried out in any conventional briquetting or pelleting equipment to produce briquettes, or pellets of any desired shape. Thus, the briquetting equipment may be molds or rolls in which the mixture is subjected to pressure. Alternatively, extrusion equipment may be used to extrude the mixture in the form of rods of any prescribed cross-section, and the rods may be cut into desired lengths to produce the shapes required. Surface-tension pelletizing equipment can, of course, be used.

The size and form of the shapes will be dictated by the final use to which the shapes are put. For the reduction of phosphorus in conventional arc-type furnaces, the preferred size is a shaped pillow approximately x /8" x /2". For blast furnaces, the size is approximately 2" x 1". For cupola-type furnaces, 6" x 4" pillows may be required.

All of these sizes have been successfully produced by these forming methods.

THE CURING STAGE The shapes so formed from this calcinate and binder blend are pyrophoric and unstable and cannot be stored in bulk. They are moved directly to the curing stage wherein the co-polymerization is initiated and sustained by subjecting the green shapes to treatment with, or without, heat in an atmosphere containing from 2.5% to 21% oxygen. The composition of this atmosphere may be achieved by use of 100% air at low temperatures and low bed heights or by dilution of the air with gases (e.g., carbon monoxide, nitrogen, flue gas, or carbon dioxide) which are inert to the shapes and to the volatile hydrocarbonaceous components of that portion of the binder which is substantially unreacted.

Preferably, this co-polymerization is achieved at the maximum reaction temperature consistent with the amount and nature of the binder and yet below the ignition point of the volatile hydrocarbonaceous components of the binder which may exist in combustible concentrations (outside the massive shape). The temperature must not exceed 50 F. below the coking point of the binder as determined in the ASTM distillation by that point at which the coke begins to appear on the side of the distillation flask. Such coking of the binder must be avoided since that quantity of binder which forms coke during curing reduces, directly, the amount of co-polymerization of the binder and calcinate. These co-polymers form the homogeneous precursors of the chemically uniform, physically strong, coke briquettes.

Curing has been effected at room temperature in 100% air oxygen) by holding the shapes under such conditions for 4 days with the shapes so distributed that the heat generated is readily dissipated.

Curing is practically and preferably accomplished by subjecting the green shapes to an atmosphere of 2.5 %21% by volume of oxygen at maximum temperature (450500 F.) for 90 to 180 minutes, preferably about 2 hours. The curing conditions that must be maintained for an acceptable product are a function of oxygen concentration in the curing atmosphere, temperature of the curing environment, thickness or height of the bed of massive shapes, and the rate at which heat is introduced and removed from the bed. Oxygen is needed in this stage as the catalysts or catalytic raw material. If the green shapes are subjected to temperatures above the softening point of the unreacted binder in concentrations of oxygen below 2.5%, disintegration of the shapes takes place at an extremely rapid rate. On the other hand, at temperatures approaching the coking temperature for a given binder and in beds of massive shapes above 24" in height, combustion of the hydrocarbonaceous volatile components of the binder occurs where the oxygen concentration exceeds 4% by volume of the entering curing atmosphere. Hence, under such conditions, the oxygen concentration should be maintained below 4% by volume. With beds of lesser height, the oxygen concentration may be increased accordingly. With beds of 6 or less in height, 20% oxygen (air) may be used in the curing medium.

It is obvious to one skilled in the art that various combinations of these variable quantities within the limits specified may be successfully employed.

This catalytic effect of oxygen may be enhanced, if so desired, by the addition of other catalysts during the cur ing process. Such catalysts may be incorporated in the green shapes before curing. Such incorporation may be made in gaseous, solution or solid form during blending, or in gaseous or solution form in the curing atmosphere. Suitable catalysts are boron trifiuoride and its complexes, aluminum chloride, hydrogen peroxide, phosphoric acid, etc. The amount of such catalyst employed may be from 0.1% to 5% based on the weight of the shapes. Maximum or near maximum strengths result, for example, with the boron trifluoride complexes and aluminum chloride in about 60 minutes curing time. In the case of hydrogen peroxide or phosphoric acid, minutes curing time gives maximum strength briquettes.

The velocity of the curing atmosphere passing through the bed of green massive shapes is a function of the geometry of the vessel used to contain these shapes. In the case of a 9 inside diameter vertical shaft, wherein the bed height was maintained at 4 to 6 feet, a satisfactory velocity was found to be 6 cubic feet per second.

The cured shapes are pyrophoric and should not be stored except in an environment which will prevent spontaneous ignition. If such uncontrolled ignition takes place, some of the cured shapes are not only consumed, but the remainder may be damaged beyond recovery.

THE COKING STAGE The cured shapes are subjected to coking at temperatures and times of such magnitude as to insure the reduction of the volatile combustible content (VCM) to a value below 2%. At the same time, this treatment effects an increase in strength and helps create that degree of reactivity specified for the end product. This is normally accomplished at temperatures above 1500 F. for at least 5 minutes in an atmosphere substantially free of carbon dioxide, water vapor and oxygen. At 1500 F. a minimum time of 15 minutes is required; at 1700 F. a minimum time of 10 minutes is required. At 1500 F. coking can be continued for about one hour without loss of reactivity. At 1700 F. coking can be continued for about 40 minutes without loss of reactivity.

The effect of higher temperatures is to increase the strength (resistance to crushing pressures) and decrease the chemical reactivity. These effects are also achieved by increasing the residence time at any given temperature. Temperatures in excess of 1750 F. are employed where a low reactivity product is desired. At temperatures as high as 4000 F. with a residence time of about 90 minutes a product results having high strength but low chemical reactivity suitable for structural uses such as fabrication of piping and vessels for the chemical industry, and for cathode liners in furnaces employed for the reduction of aluminum bearing ores to the virgin metal.

Flue gas passed through an incandescent bed of carbon to reduce the carbon dioxide content to below 10% by volume is a desirable medium for supplying coking heat to the shapes. Hydrogen, carbon monoxide, nitrogen, hydrocarbon gases, and the tar-free gases generated in the calciner may be used for this purpose.

This stage results in coke formation from the copolymerized binder and calcinate in the cured shape to produce a chemically and physically uniform carbon structure in the final product.

The coking may be effected in a coking kiln, desirably a vertical kiln, into the top of which the cured shapes are introduced and gravitate downward countercurrent to the hot gases. Alternatively, the coking may be effected on a traveling grate passing through a suitable furnace.

The coked briquettes are cooled to a temperature (about 500 F.) at which exposure to air is not detrimental, or to a lower temperature, if desired. Such cooling may be effected by passing cooling gas over or through a bed of coked shapes. This gas must be substantially free of carbon dioxide, water vapor and oxygen. Desirably, it is effected in the lower portion of the shaft kiln, in the upper portion of which the cured shapes are coked.

The resultant briquettes withstand crushing pressures of at least 3000 pounds per square inch, remain stable under all operating and storage conditions, are exceptionally resistant to abrasion, and possess other desirable properties; by observing the necessary conditions herein disclosed, briquettes of desired chemical reactivity result, including briquettes which react uniformly and are eminently satisfactory for use in metallurgical furnaces, such as blast and phosphorus furnaces.

Referring now to FIGURE 2, which shows a preferred arrangement of equipment for practicing the process of this invention, 1 indicates the pulverized coal feed to a screw conveyor 2 which discharges continuously into the catalyzer 3. The catalyzer contains a fluidized bed 4 of the pulverized coal particles. The fluidized bed 4 is activated by a hot gas stream 5 containing. steam but no air. The hot gas stream 5 may be controlled to maintain the desired atmosphere in the catalyzer 3. The catalyzer is equipped with an internal cyclone separator 6 through which gases evolved in the catalyzer are discharged through line 7. The cyclone separator 6 also removes entrained coal particles from the gas and returns the particles to the fluidized bed 4.

The catalyzer 3 discharges coal continuously through line 8 into the carbonizer 9. The carbonizer contains a fluidized bed 10 of the catalyzed coal particles. A stream of inert gas 11 is supplied as the fluidizing medium. The carbonizer 9 is equipped with an internal cyclone separator 12 through which gases evolved in the carbonizer are discharged. A gas take-off line 13 leads from the cyclone separator 12 to the condenser 30 hereinafter described. The cyclone separator 12 also removes char particles from the gas and returns the particles to the fluidized bed 10.

The carbonizer 9 discharges char continuously through line 14 into the calciner 15. The calciner contains a fluidized bed 16 of the char particles. A stream of hot air and inert gas 17 is supplied as the fluidizing medium. The calciner is equipped with an internal cyclone separator 18 through which fuel gas evolved in the calciner 15 is discharged through line 19. The cyclone separator 18 also removes char particles from the fuel gas and returns the particles to the fluidized bed 16.

The calciner 15 discharges calcined char continuously through line 20 into the cooler 21. The cooler contains a fluidized bed 22 of calcined char particles fluidized by a stream of inert gas supplied through line 23. The cooler is equipped with an internal cyclone separator 24 through which gases are discharged through line 25. The cyclone separator also removes char particles from the gas and returns the particles to the fluidized bed 22. The cooler 21 is also equipped with internal cooling coils 26 through which a suitable cooling medium may be circulated. Calcinate is continuously discharged from the cooler 21 through a rotary valve 27, then through a line 28 to the blender 29.

The tar recovery system comprises a condenser 30 supplied with a circulating cooling liquid to condense the tar and a portion of the water vapor in the gas which enters the condenser 30 from line 13. Fuel gas leaves the condenser through line 31. Tarry condensate leaves the condenser 30 through line 32 and is discharged into the decanter 33. Tar from the decanter is pumped through line 34 to the conditioner 35. The conditioner is equipped with an agitator 36. The tar in the conditioner can be heated while being agitated and is air blown by air introduced at 37 to remove moisture and raise the tar softening point. Excess gas is removed through line 38. Tar binder is pumped from the bottom of the conditioner through line 39 to the blender 29.

The blender 29 discharges the calcinate-tar-mixture through line 40 into the briquette former 41 which produces briquettes. The briquettes are discharged onto conveyor 42 which communicates with the curing oven 43; A stream of hot gas is recycled through the curing 14 oven by blower 44; this gas is heated in the gas heater 45. The desired oxygen content of the recycle gas is made up by supplying air through line 46. Waste gases evolved in the curing oven are discharged through line 47.

The cured briquettes are discharged continuously from the curing oven 43 into the coker 48. The cured briquettes move slowly through the coker 48 through a flowing stream of inert reducing gas which is continuously removed from the coker by blower 49; the gas thus removed passes through the gas cooler 50. The cooled gas re-enters the coker through line 51 near the discharge end to cool the coked briquettes. A portion of the cooled gas passes through a heater 52 and enters the coker through line 53. This gas maintains a high enough temperature to coke the cured briquettes entering the coker 48. Fuel gas evolved in the coker is discharged through line 54. The coked briquettes are discharged into a conveyor 55 and removed to storage.

The following examples are illustrative of the process of this invention. It will be appreciated that this invention is not limited to these examples.

In all examples, coal was ground in a hammer mill having a inch mesh screen to produce finely divided coal particles, 100% of which passes a No. 14 Tyler screen size, and of which. was retained on a No. 325 Tyler screen size.

The processing of this finely divided coal was carried out in equipment, in general, of the type shown in FIG- URE 2 of the drawings.

Example 1 involves a sub-bituminous coal, and EX- ample 2 involves a lignite, both identified in Table I which follows: (In this table, D.B. means dry basisi) GENERAL ANALYSIS Heating value (Ash 10,700 11,473

Free, Gross B.t.u.).

Moisture, wt. percent. 18 1.9.

Volatile Matter, wt. 2.7 l. 45.3.

percent, D.B.

Fixed Carbon, wt. 53.2 38.2

percent, D.B.

AsiIDJ, wt. percent, 4.1 16.5

Elemental Analysis,

wt. percent, D.B.:

The conditions of each of the stages or steps are given in Table II, which follows:

Table 11 Example 1 Example 2 Catalyzing:

Length of Run, Hours 11. 9 5. 4 Total Solids Fed, lbs 32.1 31 Catalyzer Inside Diameter, Inches 3. 07 3.07 Temperature of Fluid Bed, F 400 400 Residence Time, Minutes 62 24 Fluidizing Medium:

Superficial Velocity, ft./sec 0. 8 0.8 Composition, Volum percent Nitrogen 22. 8 24. 0 Steam 77. 2 76.0 Carbonizing:

Length of Run, Hours 7. 6 5. 7 Total Solids Fed, lbs 24. 8 28. 3 Carbonizer Inside Diameter, Inches 3.07 3.07 Temperature of Fluid Bed, F 880 850 Residence Time, Minutes 51 31 1 5 Table II-Continued Example 1 Example 2 Carbouizing:Continued Fluidizing Medium:

Superficial Velocity, itjsee O. 6 0. 6 Composition, Volume percent:

Oxygen 22. 7 2. 7 Nitrogen. 48.1 47. 7 Steam 49.2 49.6 Calcining:

Length of Run, Hours 5. 5 3. 6 Total Solids Fed, lbs 17.0 14.2 Caleiner Inside Diameter, Inches 3.07 3.07 Temperature of Fluid Bed, F 1,600 1, 000 Residence Time, Minutes.... 61 40 Fluidizing Medium:

Superficial Velocity, it./sec. 1. 2 1.0 Composition, Volume peree Oxygen.. 2.4 2.4 Nitrogen. 97.2 97. 6 Cooling:

Temperature of Fluid Bed, F 400 150 Composition of Fluidizing 1\ vol. percent... 1 Nitrogen l Nitrogen Temperature 80 80 Blending:

Kind of Binder Blown tar from carboniza- Hon-140 Softening Point Amount of Binder, wt percent of Total Mix 19 20 Extrusion Extrusion 20,000 20,000 Size of Shapes, I

meter x Inches High. 1.125 x 75 1.125 x .75 Curing:

Bed Heights, Inches. M Temperature of the g A phere, F 450;};10 400:1;10 Composition of the Curing Atmosphere, vol. percent:

Oxygcn 21 21 Inerts 79 79 Residence Time of Shapes, Minutes... 120 120 Coking:

Bed Heights, Inches Temperature of the Coking Atmosphere, F 1,700 1,700 Residence Time, Minutes 10 10 Composition of the Coking Atmospherc, Vol. percent:

Hydrocarbons. 5 Nitrogen 95 05 Coke Yield: Wt. percent of Coal, D.B 59. 2 G2. 4

The physical and chemical properties of the coke shapes produced in Examples 1 and 2 are given in Table III hereinafter.

In Table III, ASG is the apparent specific gravity at 15.5" C. calculated from the weight and dimensions of the coked extrusions or shapes;

TI is the Tumbler Index determined by the procedure given in ASTD D-441; I

RC is the resistance to crushing in lbs/in. determined by measuring the gauge reading at which a 1 /8 inch x 4 inch cylinder crushed under hydraulic pressure applied to its flat surface;

CR-CO is the reactivity in carbon dioxide measured by the percentage amount of the coke shape, sized to pass through a 20-mesh screen but retained on a 28-mesh Tyler screen, consumed in one hour in a stream of carbon dioxide at 900 C. and passed over the sample at a rate of 400 ml./ min. in a tube of about 1-inch inside diameter. In this test, each sample was crushed and screened. 500 mg. weighed out on a balance of 0.1 sensitivity were placed in a Gooch crucible cut down to fit with clearance in the silica tube of the furnace. The sample made a bed of A; inch in diameter and inch deep. The samples were flushed clean of air by passing argon thereover at a rate of 370 ml./min. for ten minutes.

The chemical analyses were made by procedures outlined in the Bureau of Mines Bulletin No. 492, entitled Methods of Analyzing Coal and Coke, by A. C. Fieldner and W. A. Selvig. The values given are in weight percent on a dry basis.

VM means volatile matter; the other abbreviations under Chemical Analysis are the chemical symbols or formulae for the elementsand compounds identified thereby.

C/H is the carbon to hydrogen weight ratio.

H /C is the hydrogen to carbon atom ratio.

In general, the products of the above two examples have substantially the same properties as the products produced by our aforesaid co-pending application and disclosed and claimed in our applications, Serial Nos. 31,316 and 31,317, filed May 24, 1960. The products produced by the process of this invention had an open and connected pore structure and a homogeneous appearance. No visible ditlerence between coke derived from the binder and that derived from the calcinate was evident upon examination under a microscope at magnifications of 50 and x.

It will be noted that the present invention provides a process for treating coals of high oxygen content containing at least 15% oxygen MAF to produce physically strong carbonaceous materials suitable for use among other uses as a metallurgical carbon. The process of this invention can be carried out to produce carbonaceous products of high strength and having controlled chemical reactivity; thus products of different reactivities from highly reactive (many times that of high temperature byproduct coke) to comparatively inert material and having desired predictable physical characteristics can be produced from high oxygen content coals by the process of this invention.

It will be further noted that the present invention results in the production from coals of high oxygen content of a calcinate product, which is physically strong, abrasive resistant, homogeneous and reacts readily and uniformly with dioxide, also steam and oxygen. This calcinate can be used as such, for example, as a raw material for water gas or other gas reactions in the place of coal or coke, or for efiecting the reduction of ores, as in sintered iron processes. It can be combined with a binder and the mixture compresesd to produce a dense unit of any desired shape or size which is cured and coked as hereinabove disclosed to produce coke shapes possessing qualities rendering them eminently satisfactory for such uses as smelting of phosphorous and other ores, and carrying out chemical reactions. By processing under conditions herein disclosed, a high strength product of low chemical reactivity results, if desired; such products are suitable, among other uses, as a structural material in the chemical field.

All percentages in this specification, unless otherwise indicated, are on a weight basis.

Since certain changes may be made in carrying out the above described method without departing from the scope of the invention, it is intended that all matter contained in the above description shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. A process of producing carbonaceous material from coal having an oxygen content on a moisture and ashfree basis of at least 15% by weight which comprises, heating particles of said coal to a temperature within the range of 250 F. to 500 F. in an atmosphere free of oxygen derived from a source extraneous to the coal for from minutes to 3 hours. to produce catalyzed coal particles conditioned so that in the next heating stage the amount of hydrocarbonaceous matter in the coal particles is reduced; heating the catalyzed coal particles to a still higher temperature but not exceeding 1200 F. and-maintaining them at said higher temperature for from to 60 minutes to evolve'vapors and produce char which has the essential structure and density of the parent coal, but has a markedly lower volatile combustible material content than the parent coal; and heating the char to a still higher temperature within the range of from 1400 F. to 1800 F. and maintaining the heated char at said higher temperature for a time interval to produce calcinate.

2. A process of producing carbonaceous shapes from coal having an oxygen content on a moisture and ashfree basis of at least by weight which comprises, heating particles of said coal'to a temperature above 250 F. and below that at which substantial amounts of tarforming vapors evolve for a time interval sufficient to produce catalyzed coal particles conditioned so that in the subsequent carbonizing stage the hydrocarbonaceous matter is reduced; heating the catalyzed coal particles to a still higher temperature and maintaining them at said higher temperature for a time interval sufficient to evolve vapors and produce char which has a markedly lower volatile combustible material content than the parent coal; heating the char to a still higher temperature and maintaining the heated char at said higher temperature for a time interval suflicient to produce hot calcinate, cooling said hot calcinate particles; blending said cooled calcinate particles with a bituminous binder; subjecting the blend to a forming pressure to produce green shapes; curing the green shapes thus produced in an atmosphere containing at least 2.5% by volume of oxygen to produce cured shapes; coking the cured shapes; and cooling the coked shapes.

3. A process of producing carbonaceous shapes from coal having an oxygen content on a moisture and ashfree basis of at least 15% by weight which comprises, heating particles of said coal to a temperature above 250 F. and below that at which substantial amounts of tar-forming vapors evolve for a time interval sufiicient to produce catalyzed coal particles conditioned so that in the subsequent carbonizing stage the hydrocarbonaceous matter is reduced; heating the catalyzed coal particles to a still higher temperature and maintaining them at said higher temperature for a time interval suflicient to evolve vapors and produce char; heating the char to a still higher temperature and maintaining the heated char at said higher temperature for a time interval sufficient to produce hot calcinate; substantially instantaneously cooling said hot calcinate particles; blending said cooled calcinate particles with a bituminous binder having a softening point within the range of 100 F. to 225 F. in the proportions of 75% to 90% by weight of calcinate to 10% to by weight of binder; subjecting the blend to a forming pressure to produce green shapes; curing the green shapes thus produced in an atmosphere containing from 2.5% to 21% by volume of oxygen at a temperature of from 450 F. to 500 F. for 90 to 180 minutes; coking the cured shapes at a temperature above 1500 F.; and cooling the coked shapes to a temperature below 500 F.

4. The method of producing chemically reactive carbonaceous material from bituminous coals having an oxygen content on a moisture and ash-free basis of at least 15% by weight, which-comprises, heating for 5 minutes to 3 hours particles of said coal in an atmosphere consisting of inert gas and steam at a temperature of from 250 F. to 500 F.; thereafter further heating the thus treated coal particles to a temperature of from 500 F. to 1200 F. and maintaining the coal particles at said 18 temperature for from 10 to 60 minutes; and thereafter heating the thus treated coal to a temperature of from 1400 F. to 1800 F. in an atmosphere substantially free of carbon dioxide and water vapor and maintaining them at said temperature for a time interval suflicient to produce calcined char.

5. The method of producing reactive carbonaceous material from coal having an oxygen content on a moisture and ash-free basis of at least 15% by weight, which comprises, heating particles of said coal in a fluidized bed to a temperature of from 250 F. to 500 F. in an atmosphere containing inert gas and steam for a time interval suflicient to produce catalyzed coal particles conditioned so that in the next heating stage the hydrocarbonaceous matter is reduced; heating the catalyzed coal for from 10 to 60 minutes by introducing it into and maintaining it in a fluidized bed at a temperature above the bed temperature of the first mentioned bed and below 1200 F.; thereafter heating the thus treated coal particles in another fluidized bed to a temperature of from 1400 F. to 1850 F., maintaining the coal particles in said last mentioned fluidized bed for a time interval long enough to produce calcined char; and thereafter cooling the calcined char particles in a non-oxidizing atmosphere.

6. The method of producing physically strong, chemically reactive carbonaceous material from coal having an oxygen content on a moisture and ash-free basis of at least 15% by weight, involving heating particles of said coal in a first fluidized bed in an atmosphere containing nitrogen and steam and free of oxygen to a tem perature of from 250 F. to 500 F. for from 5 minutes to 3 hours; removing the thus heated coal particles from said first mentioned fluidized bed and introducing them into a second fluidized bed where they are heated to a temperature of from 500 F. to 1200 F. for from 10 to 60 minutes, said heating being effected in part at least by combustion of a portion of the coal, introducing fluidizing flue gas into the second fluidized bed at a temperature not less than that of the bed temperature; removing the thus heated coal particles from the second fluidized bed and introducing them into a third fluidized bed where they are heated to a temperature of from 1400 F. to 1800 F. for from 7 to 60 minutes in a fluidizing gas atmosphere consisting of flue gas substantially free of carbon dioxide, oxygen and water vapor; and thereafter withdrawing the thus heated coal particles and introducing them into a fourth fluidized bed Where they are cooled by a fluidizing flue gas medium substantially free of carbon dioxide, oxygen and water vapor.

7. The method of producing physically strong, chemically reactive carbonaceous shapes from coal having an oxygen content on a moisture and ash-free basis of at least 15% by weight, which comprises, heating particles of said coal in an atmosphere containing steam and free of added oxygen to a temperature of from 250 F. to 500 F. for a time interval sufficient to produce catalyzed coal particles conditioned so that in the next heating stage the hydrocarbonaceous matter is reduced; thereafter heating the catalyzed coal particles to a still higher temperature but not exceeding 1200 F. for a time interval sufiicient to evolve vapors and produce char having a markedly lower volatile combustible material content; thereafter heating the char to a temperature of from 1400 F. to 1800 F. in an atmosphere substantially free of carbon dioxide and water vapor and maintaining them at said temperature for a time interval to produce hot calcinate; then cooling the hot calcinate; mixing the cooled calcinate with a bituminous binder in the proportions of 75% to by Weight of calcinate to from 10% to 25% by weight of binder; compressing the resultant mixture to produce green shapes; curing the green shapes by passing them through a heating zone at a temperature of from 450 F. to 500 F. in an atmosphere containing from 2.5% to 21% by volume of oxygen for amazes 1.9 from 90 minutes to 3 hours to produce cured shapes; and coking the cured shapes to reduce the volatile content to not exceeding 3% by weight in an atmosphere substantially free of carbon dioxide, water vapor and oxygen at a temperature of from 1500 F. to 1750 F.

8. The method of producing physically strong, carbonaceous briquettes from coal having an oxygen content on a moisture and ash-free basis of at least 15% by weight, which comprises, heating particles of said coal in a first fluidized bed in an atmosphere containing steam and free of added oxygen to a temperature of from 250 F. to 500 F. for from 5 minutes to 3 hours; removing the thus heated coal particles from said first mentioned fluidized bed and introducing them into a second fluidized bed where they are heated to a temperature not exceeding 1200 F. for from to 60 minutes, said heating being effected in part at least by combustion of a portion of the coal, introducing fluidizing flue gas into the second fluidized bed at a temperature not less than that of the bed temperature; removing the thus heated coal particles from the second fluidized bed and introducing them into a third fluidized bed where they are heated to 1400 F. to 1800 F. for from 7 minutes to 1 hour in a fluidizing gas atmosphere consisting of flue gas substantially free of carbon dioxide and water vapor; thereafter withdrawing the thus heated finely divided coal particles and introducing them into a fourth fluidized bed where they are cooled by a fluidizing flue gas medium to a temperature not exceeding 400 F., said cooling medium being substantially free of carbon dioxide, oxygen and water vapor; mixing the cooled carbonaceous material with a bituminous binder in the proportions of 75% to 90% by weight of reactive carbonaceous material to from 10% to 25% by weight of binder; briquetting the resultant mixture; curing the briquettes by passing them through a heating zone at a temperature of from 450 F. to 500 F. in an atmosphere containing from 2.5% to 21% by volume of oxygen, maintaining the briquettes in said zone for from 90 to 180 minutes to produce cured briquettes; and coking the thus cured briquettes to reduce the volatile content to not exceeding 3% by weight in an atmosphere substantially free of carbon dioxide, water vapor and oxygen at a temperature of from 1500 F. to 4000 F. for a time interval suflicient to produce coked shapes having the desired chemical reactivity.

9. A method for the conversion of coals from the group consisting of bituminous coals and lignites containing at least oxygen by weight on a moisture and ash-free basis to pitch-bonded carbon products possessing high mechanical strength, which method comprises the following steps: step 1, heating said coal in pulverized form in an atmosphere containing steam but no oxygen derived from a source extraneous to the coal at a temperature below that at which distillate vapors evolved condense as tars and above that at which water, when present, vaporizes, to produce a product which is nonagglomerating in step 2; step 2, heating the product of step 1 to a temperature at which evolution of tar-forming vapors takes place at a rate insuflicient to cause permanent swelling, distortion and disruption of the product of step 1, said heating being for a time interval long enough to materially reduce the volatile matter but not long enough to impair the pyrophoric reactivity of the product of step 2; step 3, heating the product of step 2 to a temperature not exceeding 1800 F. in an atmosphere containing only suflicient oxygen for the coal particles to reach said heating temperature and for a period of time to effect reduction of the volatile content of the product of step 2 to less than 3% by weight Without substantial impairment of the pyrophoric reactivity of the product of step 3; step 4, blending the product of step 3 with pitch in amount sufficient to coat the product of step 3 and produce a mechanically strong product when subjected to compression; step 5, compressing the blend from step 4; step 6, curing the comprissed product of step 5 by rapid heating in a mildly oxidizing atmosphere at a temperature sufficient to cause copolymerization of the pitch binder and the product of step 3 to take place but not exceeding 50 F. below the temperature at which coking of the pitch takes place; and, step 7, coking the product of step 6 at a temperature exceeding 1500 F. in an inert atmosphere for a time interval to produce a high strength product having the desired chemical reactivity.

10. A process of producing carbonaceous material from coal having an oxygen content on a moisture and ash free basis of at least about 15 by weight which comprises, heating particles of said coal to a temperature above 250 F. and below that at which substantial amounts of tar-forming vapors evolve in an atmosphere containing substantially no oxygen derived from a source extraneous to the coal, for a time interval suflicient to produce coal particles conditioned so that in the subsequent carbonizing stage the coal particles are nonagglomerating; heating the thus heated coal particles to a still higher temperature at which vapors which condense as tars are evolved and maintaining said heated particles at said higher temperature for a time interval sufiicient to effect polymerization of the heated coal particles and evolution therefrom of substantially all vapors which condense as tars, producing a char of markedly lower volatile combustible material content than the parent coal and substantially free of tar-forming vapors; and heating the char thus produced to a still higher temperature for a time interval suflicient to produce calcined char particles.

11. A process for the conversion of coals from the group consisting of bituminous coals and lignites containing at least 15 oxygen by weight on a moisture and ash free basis which comprises the following steps: step 1, heating said coal in particle form to a temperature above 250 F. and below that at which substantial amounts of tar-forming vapors evolve in an atmosphere containing steam but no oxygen derived from a source extraneous to the coal, to produce a product which is non-agglomerating in step 2; step 2, heating the product of step 1 to a higher temperature at which vapors which condense as tars are evolved, and maintaining said heated particles at said higher temperature for a time interval suflicient to effect polymerization of the heated coal particles and evolution therefrom of substantially all vapors which condense as tars, producing a char of markedly lower volatile combustible material content than the parent coal and substantially free of tar-forming vapors; and step 3, heating the product of step 2 to a still higher temperature to produce calcined char particles having a volatile combustible material content below 3% by weight of the char particles as produced in said step 3, which higher temperature is below the temperature at which the structure and chemical reactivity of the parent coal particles are deleteriously affected.

12. A process for the conversion of coals from the group consisting of bituminous coals and lignites containing at least 15% oxygen by weight on a moisture and ash free basis which comprises the following steps: step 1, heating said coal in particle form to a temperature above 250 F. and below that at which substantial amounts of tar-forming vapors evolve in an atmosphere containing steam but no oxygen derived from a source extraneous to the coal, to produce a product which is non-agglornerating in step 2; step 2, heating the product of step 1 to a higher temperature at which vapors which condense as tars are evolved, and maintaining said heated particles at said higher temperature for a time interval sufiicient to effect polymerization of the heated coal particles and evolution therefrom of substantially all vapors which condense as tars, producing a char of markedly lower volatile combustible material content than the parent References Cited in the file of this patent UNITED STATES PATENTS 1,943,291 Abbott Jan. 16, 1934 10 Howard Jan. 15, Williams Sept. 3, Kruppa et a1 Dec. 3, Brown et a1 I an. 20, Gorin et al Aug. 28,

FOREIGN PATENTS Australia Oct. 23,

Claims (1)

1. A PROCESS OF PRODUCING CARBONACEOUS MATERIAL FROM COAL HAVING AN OXYGEN CONTENT ON A MOISTURE AND ASHFREE BASIS OF AT LEAST 15% BY WEIGHT WHICH COMPRISES, HEATING PARTICLES OF SAID COAL TO A TEMPERATURE WITHIN THE RANGE OF 250*F. TO 500*F. IN AN ATMOSPHERE FREE OF OXYGEN DERIVED FROM A SOURCE EXTRANEOUS TO THE COAL FOR FROM 5 MINUTES TO 3 HOURS TO PRODUCE CATALYZED COAL PARTICLES CONDITIONED SO THAT IN THE NEXT HEATING STAGE THE AMOUNT OF HYDROCARBONACEOUS MATTER IN THE COAL PARTICLES IS REDUCED; HEATING THE CATALYZED COAL PARTICLES TO A STILL HIGHER TEMPERATURE BUT NOT EXCEEDING 1200*F. AND MAINTAINING THEM AT SAID HIGHER TEMPERATURE FOR FROM 10 TO 60 MINUTES TO EVOLVE VAPORS AND PRODUCE CHAR WHICH HAS THE ESSENTIAL STRUCTURE AND DENSITY OF THE PARENT COAL, BUT HAS A MARKEDLY LOWER VOLATILE COMBUSTIBLE MATERIAL CONTENT THAN THE PARENT COAL; AND HEATING THE CHAR TO A STILL HIGHER TEMPERATURE WITHIN THE RANGE OF FROM 1400*F. TO 1800*F. AND MAINTAINING THE HEATED CHAR AT SAID HIGHER TEMPERATURE FOR A TIME INTERVAL TO PRODUCE CALCINATE.

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