US2841478A - Process for the manufacture of briquets, particularly fuel briquets - Google Patents

Description

United PROCESS FOR THE MANUFACTURE OF BRIQUETS, PARTICULARLY FUEL BRIQUETS N Drawing. Application January 17, 1955 Serial No. 482,399

Claims priority, application Netherlands January 23, 1954 8 Claims. (Cl. 44-15) According to the present invention briquets are manufactured by wetting the starting material with a conversion product which has been prepared by treating one or more higher carbohydrates or carbohydrate ethers with a dilute aqueous solution of an organic carboxylic acid, shaping the thus treated material under the application of pressure, and drying the briquets thus obtained, if desired, with heating. The invention is particularly suitable for the manufacture of briquets from fuel, such as coal and brown coal up to the most finely divided form, peat moor and lowland peat, suitable for the manufacture of lumps of peat.

An important advantage of the present process is that .for the manufacture of the briquets no pitch or the like is used at all. The use of pitch namely has the disadvantage that the briquets burn under development of a smoke from which a large quantity of soot deposits. The fuel briquets manufactured according to the present process give less, at least not more soot than the fuel which has been used, than the starting material. Moreover the briquets do not disintegrate during burning.

Coal sludge and/ or coal dust may be started from, but one of the advantages of the present process is that also less finely divided material up to a size of approximately 0.6 cm., may be included in the briquets.

In general the briquetting according to the present process is carried out as follows: the starting material is intimately mixed with a quantity of the above-mentioned conversion product which has been brought at the most suitable concentration beforehand, if desired. The moisture content required varies from approximately 6 to approximately 20% of the weight of the starting material, depending on the nature and/or fineness and/or degree of humidity thereof. The water content may be adjusted beforehand, whereupon the conversion product, diluted or not, is added, adapted to the degree of humidity of the starting material, or the conversion product is added at once in the correct concentration. The required proportion of the solid conversion product is very small: proportions between 0.1 and 1.0% may already be sulficient to produce a solid, Water-resistant briquet. The preferred moisture content, at slight pressing, amounts to approximately 10% the weight of the solid product obtained from the conversion product preferably amounting to approximately 0.5% calculated on the weight of the starting material to be briquetted.

The moist mass obtained by admixing the solution to the starting material now is moulded, e. g. with the aid of a briquetting press. In the manufacture of briquets, in which pitch is incorporated as a binding agent, pressures up to approximately 125 atmospheres are usually applied; in the present briquetting process a low pressure is sufiicient, however. A pressure of a few atmos pheres is alresdy sufficient to obtain a briquet with good mechanical properties. When a higher pressure is applied the proportion of binding agent may be reduced.

flies P tent i No. 482,400, filed January 17, 1955.

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During pressing a part of the moisture may already be removed from the briquets, they may be dried at the air. The drying process is accelerated by heating. For the heating use may be made of a drying drum. Owing to the heating the hardening of the binding agent proceeds more rapidly by oxidation at the air. The preparation of the binding agent and the property of hardening at the air have been described in copending application Serial As disclosed in said copending application, the carbohydrates or carbohydrate ethers serving as starting materials for the preparation of the conversion product used for the binding agent may include starch, dextrin, and Tylose (a brandname for cellulose ethers, such as, for example, methylcellulose and carboxymethylcellulosc). The organic carboxylic acids used for the conversion may include acetic, propionic, butyric, oxalic, tartaric, and citric acids.

The briquets obtained according to the invention not only display the correct coherence and shape resistance, but they also have a good resistance against less. favorable conditions, such as a long stay in the open air. The ash content of the briquets displays, a, reduction in respect of the starting material. Moreover, the briquets give a higher heat-effect which probably is to be attributed to a more complete combustion. The briquets easily start burning and they do not disintegrate during burning. When using fuel with a low content of volatile matter the briquets do not form more soot than the fuel from which they have been made. The briquets made from coal with a high content of volatile matter form less soot under all circumstances than the fuel from which they have been manufactured.

The invention is elucidated by the following examples:

Example I A conversion product was prepared in the manner as described in copending application Serial No. 482,400 filed January 17, 1955 by dissolving 30 g. of dextrin in 1 liter of water and treating with 55 ml. of 80% acetic acid. After completion of the reaction a few drops of ammonia were added, sufficient to remove the sharp odor.

A quantity of coal material, consisting of 25% of coal sludge of low volatility and of coal dust of high volatility with a maximum particle size of approximately 5 mm. was intimately mixed with the abovedescribed solution, calculated on 10% of the weight of the raw material to be briquetted, and thereupon under slight pressure (approximately 4 at.) shaped to briquets. The briquets were hereupon dried by heating to approximately 120 C.

The ash content of the original coal mixture amounted to 19.4% and in dry condition to 19.7%, the water content to 1.5% and the content of volatile substances in the dried coal to 18.0%. The ash content of the briquets, on the contrary, amounted to 11.3% of the dry coal.

The combustion heat of the starting material amounted to 6800 cal./g., whereas the combustion heat of the briquet amounted to 7540 cal./ g. The bulk specific gravity of the coal amounted to 1.44 against that of the briquet to 1.38.

The briquets manufactured in the way described ignite easily and burn with a rather long, little sooting flame. During degassing a rather swollen coke is formed which is converted into fairly hard pieces. The water-resistance of the briquet is good.

Example II 6 g. of Tylose (cellulose ether) were dissolved in l l. of water and treated with 7.5 ml. of acetic acid while heating to approximately 40 C.

An amount of coal, consisting of 25% of coal sludge of low volatility and 75% of anthracite fines. up to 6 mm.

were intimately mixed with the above-described solution, calculated on 10% of the weight of the raw material to be briquetted and shaped to briquets at a pressure of approximately 4 at. Thereupon the briquets were dried by heating to approximately 120 C.

After having been immersed in water for three days the briquets still were completely intact. They had practically the same strength as before the immersion.

They ignite easily and burn practically without the forma tion of soot. The form strength on the fire is good.

What is claimed is:

1. A process for the manufacture of briquets which comprises mixing relatively finely divided coal with an aqueous solution of a single binding agent consisting essentially of the reaction product of. a low molecular weight aliphatic monocarboxylic acid with a member selected from the group consisting of starch, dextrin and methyl cellulose, the concentration of said agent in said solution providing a proportion of abut 0.1% to 1.0% by weight of the binding agent based on the weight of the coal, shaping said mixture into briquets under the action of pressure, and drying the shaped briquets.

2. A process of claim 1, wherein the concentration of said agent in the aqueous solution thereof is approximately 10%.

3. The process of claim 1 in which the acid is acetic acid.

4. The process of claim 1 in which the acid is 80% acetic acid.

5. A process for the manufacture of fuel briquets which comprises mixing finely divided coal with an aqueous solution of a single binding agent consisting essentially of the reaction product of acetic acid with methyl cellulose, shaping the mixture into briquets under the action of pressure, and drying the shaped briquets.

6. The process for the manufacture of fuel briquets which comprises mixing finely divided coal with an aqueous solution of a single binding agent consisting essentially of the reaction product of acetic acid with dextrin, shaping the mixture into briquets under the action of pressure, and drying the shaped briquets.

7. A fuel briquet comprising essentially a compressed and dried mixture of finely powdered coal and a single binding agent therefor, said binding agent being present in an amount of from approximately 0.1% to 1.0% by weight of the powdered coal and consisting essentially of the reaction product of a low molecular weight aliphatic monocarboxylic acid with a member selected from the group consisting of starch, dextrin and methyl cellulose.

8. A fuel briquet as defined in claim 7, wherein the 'said acid is acetic acid.

Adhesion and Adhesives, De Bruyne and Houwink, Elsevier Pub. Co., N. Y., 1951, page 189.

JNITED STATES PATENT OFFICE EEN'HMCATE CORRECTION Patent N00 2,841,478 July 1, 1958 I Heinrich Dohmen It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below,

In the grant,, lines 2 and 3, for assignor to N V Eldeka, of The Hague, Netherlands, a limited liahility of the Nether].ands read assignor to N, V Briko of The Hague, Netherlands a limitedliability company of the Netherlands, 5 line 12, for "N, V Eldeka; its successors" read. No V0 Briko, its successors in the heading to the printed specification, lines 5 to 7, for "assignor to Na Va Eldeka, The Hague, Netherlands, a limited liability of the Netherlands" read assignor to N, V,, Briko, The Hague; Netherlands, a limited liability company of the Netherlands u Signed and sealed this 9th day of Deceraber 1958a (SEAL) 3 Attest:

KARL Eel-LINE ROBERT co WATSON Attesting Officer Comissioner of Patents

Claims (1)

1. A PROCESS FOR THE MANUFACTURE OF BRIQUETS WHICH COMPRISES MIXING RELATIVELY FINELY DIVIDED COAL WITH AN AQUEOUS, SOLUTION OF A SINGLE BINDING AGENT CONSISTING ESSENTIALLY OF THE REACTION PRODUCT OF A LOW MOLECULAR WEIGHT ALIPHATIC MONOCARBOXYLIC ACID WITH A MEMBER SELECTED FROM THE GROUP CONSISTING OF STARCH, DEXTRIN AND METHYL CELLULOSE, THE CONCENTRATION OF SAID AGENT IN SAID SOLUTION PROVIDING A PROPORTION OF ABOUT 0.1% TO 1.0% BY WEIGHT OF THE BINDING AGENT BASED ON THE WEIGHT OF THE COAL, SHAPING SAID MIXTURE INTO BRIQUETS UNDER THE ACTION OF PRESSURE, AND DRYING THE SHAPED BRIQUETS.