US1618248A - Carbonized briquette and its manufacture - Google Patents

Description

Patented Feb. 22, 1927. I

UNITED STATES PATENT OFFICE.

No Drawing.

My invention relates to carbonized briquettes and their manufacture, my. aim being to produce a superior product, and to simplify and .cheapenmanufacture. While the invention is especially advantageous for the softer coals, yet it is also adaptable to anthracite, for example. In making briquettes, my preferred method is as follows:

Taking a non-coking and non-caking coal such as New River coal, for example, I grind it sufficiently for all to pass a screen of meshes to the linear inch, say. The coal thusoperatcd on may be mine run or screenings,preferably the latter. I grind the coal in water or by what is known as the wet-grinding process, thus eliminatin fire hazard. The resulting wet coal slu' ge is allowed to drain naturally by standing in a pile, and then mixed with binder While still wet. The amount of water retained by the ground coal after draining 1s determined,

and the percentage of binder au ed on a dry basis, according. to .avhat 1s ound by trial to give'the best results with each particular coal treated. With New River coal, I use 8% by weight of binder and 92% dry weight of coal. For binder I may use an oil distillate of an asphalt base, such as asphaltum base petroleum distillate: e; g.,

Mexican oil distillate of 11 B. gives excellent results. Such a distillate is readily obtainable and low in price.

Adding the oil binder to the wet coal, I work and knead the two together until the mass is homogeneous. Oil has a physical aflinity for coal or carbon, and displaces the water readily: accordingly, the water is easily forced out of the mass. The oil is more easily worked through and blended with the wetted coalthan it would be with dry coal. Preferably, I employ a blending or mixing machine that will approximate orv duplicate the action of a mortar and pestle.

In practice, such a machine as-a Sim son mixer or a wet pan with suspended mu ers 'is satisfactory.

The mass of coal and oil may be formed into briquettes by either of two preferred methods: extrusion through a die, or pressing in a mold. Fairly high pressure is necessary. In either case, nearly all the water remaining in the mixture is expelled as the briquette is formed, so that not more than Application filed December 3, 1925. Serial No. 78,055.

the briquettes, I prefer the plunger type, in

order that as the water is expelled from the briquette it may leak back between the piston and the cylinder. As it is extruded,the column is cut off into convenient lengths. lVhen I use a press, I prefer a mechanical or hydraulic one of the type that pushes the formed briquette throu h the mold. This forms an oil film on t e surface of the briquette. which improves the appearance of the finished product.

,VVhile the formed bri uettes may be dried or partially dried before retorting or carbonizing, yet I prefer to retort them without any special drying, thus allowing them to retain their. moisture, This is because a certain amount of moisture improves the gas yield in carbonization. In

charging the retort, I may mix the bri-- briquettes is desirable. The retorts may be.

heated externally by burning the gas generated in the retorting process, or by the combustion of coal, or by any suitable means.

The temperature and time of retorting are important, being ameans of controlling the shrinkage of the briquettes and the amount of volatile matter retained in them. By controlling the shrinkage, I am able to give the product a high apparent specific gravity, approaching that of anthracite. The volatile retained after low temperature retorting is substantial; i. e., some 10 to 12%., which is approximately the same as the volatile content of first quality anthracite. The fineness of grind ofthe original coal alsohas a bearing on the shrinkage, some coals requiring to be finer than others in order that the briquettes may attain maximum shrinkage and compactness. The temperature that I have commonly used in retorting is 500 C. (932 F.); and in low temperature carbonizin" as it is termed),'I do not exceed 550 1012 F.). In general, retorting should continue until no more gas will come off at the temperature employed: the time reuired' for this depends on the e of coal, t e size of the charge and its thic lies against the retort wall throu h which the heat is transmitted to it, etc. igh temperature carbonizing (expelling most or nearly all of the volatile) may be employed; but the briquettes thereby produced are not so satisfactory.

After retorting, the briquettes may be cooled to atmospheric (room) temperature under the protection of non-oxidizing gas. For this purpose, the products of combustion from the retort gas fires that heat the retorts may be used to preheat water, and thereby cooled below combustion tempera ture; they may then be employed as a cooling medium for the briquettes and their protective charcoal or coke. When thus cooled below combustion temperature in combustion gases, the briquettes retain a slickened looking surface, and the charcoal is preserved tor reuse.

In this process of making briquettes from bituminous coal and oil hinder, the oil holds the coal in shape while being prepared for retortin and give the desired retorting effeet at t is low temperatures indicated. The

briquettes are hard, dense and cohesive; have a pleasing appearance; and closely resemble anthracite in density, in chemica constitution (proportions of fixed carbon, volatile matter, and ash), and in physical behavior on burning (retaining their shape without caking or running together). The process can also be ada ted and extended to the briquetting of ant iracite, with suitable variation in the percent of binder (anthracite requiring more bin er than bituminous coal). The anthracite briquettes thus produced are superior to those of the rior art in both their appearance and their havior in burning.

Having thus described my invention I claim:

1. The step in the preparation of oilboncled pulverized coal for briquetting which comprises mixing wet-ground coal of predetermined moisture content with the oil binder, while wet, in approximately the prortions of nine parts of the former to one part of the latter.

2. The method of pre aring oil-bonded coal for briquettin whic comprises wetgrinding the coal, draining the ground coal to predetermined moisture content, and mixin it with the oil binder while, still wet, su stantially in the proportions of ninetytwo parts of the wet coal and eight parts of the oil binder.

essasit 3. The method of making bri uettes which comprises wet-grinding coal an mixing it, while wet, with an oil binder; and

after briquetting, retorting and carbonizing the briquettes in a non-oxidizin environment at a temperature sutlicient y low to allow them to retain a substantial proportion of volatile matter.

4. The method of making briquettes which comprises wet-grinding coal and mixing it, while still wet, with an oilbinder; forming the mixture into briquettes; and retorting and carbonizing the briquettes with carbonaceous material substantially free from volatile matter, at a temperature sufliciently low to allow them to retain a substantial proportion of volatile matter.

5. The method of making briquettes which com rises wet-grinding coal and mixing it, whi e still wet, with an oil binder; forming the mixture into briquettes; retortin and carbonizing the briquettes with car naceous material substantially free from volatile matter, at a temperature sufiiciently low to allow them to retain a substantial pro or.- tion of volatile matter; and cooling the riuettes and said material with a non-oxi- 'zin medium.

6. he method which comprises retorting and carbonizing oil-bonded coal briquettes containing not more than ten to twelve per cent of water at a temperature sufiiciently low to allow them to retain a substantial proportion of volatile matter.

7. The method which comprises retorting and carbonizing oil-bonded coal briquettes containing not more than ten to twelve percent of water in a protective non-oxidizing environment, at a temperature sufiiciently low to allow them to retain a substantial proportion of volatile matter.

8. The method which comprises retorting and carbonizin oil-bonded coal briquettes while protecte from oxidation by a covering of powdered carbonaceous material.

9. The method which comprises retorting and carbonizing oil-bonded coal briquettes at a temperature suificiently low to allow them to retain a substantial proportion of volatile matter, and cooling the briquettes in a non-oxidizing gas.

10. The method which comprises retorting and carbonizing oil-bonded coal briquettes while protected from oxidation by a covering of powdered carbonaceous material, and cooling the briquettes and said material under the protectionof a non-oxidizing s.

11. A hard briquette of hi h s ecific gravity consisting of wet-groun coa and an oil binder with a water content of not more than ten to twelve percent carbonized at low temperature and retaining'a" substantial proportion of volatile matter; having a density approaching that ofanthracite, and charac/ terized by a slickened appearance when mating anthracite coal in specific gravity; cooled under non-oxidizing conditions after in proportions of fixed carbon, volatile matcarbonization. ter, and ash, and in behavior during burning. 10 12. A hard, dense carbonized briquette In testimony whereof, I have hereunto 5 composed of wet-ground bituminous coal signed m name at Philadelphia, Pennsyland an oil binder with a water content of not Vania, this 30th day of November, 1925. more than ten to twelve percent, approxi- SAMUEL FORMAN WALTON.