US2042894A - Fuel briquette and method for the production of same - Google Patents

Description

Patented June 2, 1936 PATENT OFFIQE.

FUEL BRIQUETTE AND METHOD FOR THE PRODUCTION OF SAME Leendert Johannes Jacobus Hazelzet, Rotterdam, Netherlands N0 Drawing. Application December 21, 1933,

Serial No. 703,487. In the Netherlands January 2, 1933 2 Claims.

The invention relates to a method for producing fuel briquettes from anthracitedufi or any other fine combustible material, such as charcoalduif or cokedufi, e. g. the coke which is produced from petroleum residue or brown coal.

The purpose of the invention is the production of briquettes, the combustion qualities of which such as the forming of ashes and smoke, the rate of combustion, the forming of slag, are substantially the same as the qualities of the raw material.

A further object is to produce briquettes which have good mechanical properties, e. g. good. consistency during transportation and when burned.

Methods are already known, which are used for the production of briquettes possessing some of the qualities mentioned. More particularly if non-bituminous binding agents, such as dextrin, starch, are used, rather good results are obtained.

It is however, very difiicult to produce briquettes with low ash content, that is, a content comparable With that of the raw material.

Excellent anthraciteduif having 6% of ash content was used for example, for briquetting. The result of combustion experiments with the briquettes often showed 16% or more of ash content.

A briquette of this kind has no wide field of utility and is not economical for domestical heating purposes.

Their qualities do not measure up to the requirements for use in open fireplaces, closed circulation hearths and stoves.

These said experiments showed furthermore that the ash content contained much unburnt combustible matter; from which fact it may be deduced that the prior art briquettes simply disintegrate in the fire.

This phenomenon takes place not only with briquettes pressed with the well known pitch or tar, but also with briquettes of much better qualities as regards smoking in the fire, such for example as those pressed With dextrin or starch.

According to this invention, a quantity of sodium borate (NazBioq) or an equivalent substance which chemically corresponds to the contents of silicon dioxide (SiO2) or silicates in the ash content of the raw material, is added to the binding agent, so that at the combustion-temperature, the mixture of non-combustible substances of the briquettes sinters together so as to form a glasslike skeleton in the individual briquettes.

It is found that the ash content of the briquettes according to this invention does not difier materially from that of the raw material.

In an embodiment of the invention about /2% (in weight) of sodium borate or potassium borate is used. It is to be noted that the exact quantity of these additional substances is of great importance, since if too much is added, the briquettes slag in the fire, whereas if an insufiicient quantity of the additions is added the briquettes disintegrate in the fire.

Furthermore attention must be paid to the fact that it may be possible that the raw material contains so little silicon dioxide that the chemically corresponding quantity of the borate i. e. the quantity which suffices for forming the glasslike skeleton in the fire, may become too small to enable an exact distribution in small quantities of the said additional substance in a continuously operating briquetting plant. Furthermore, in this case the glasslike skeleton would become too brittle. In this case an extra quantity of a silicon dioxide containing substance e. g. silversand, is added to the binding agent, so that the ash content of the raw material is artificially increased to a value at which the necessary percentage of silicon dioxide is available.

The briquette according to my invention remains coherent in the fire until the very last moment.

The additional substances are preferably mixed with the binding agent before the latter is mixed with the dust to be briquetted.

If the additional substance is fed to a stream of binding agent in the usual briquetting plants by means of a container having its outlet on a rotating distributing disc, there is the danger that the usual small quantities of additional substance are not exactly distributed nor homogeneously divided in the final slurry which is to be moulded in briquettes.

Example 100 kg. of anthracite duff consisting of grains of a maximum size of 2 mm. are used for making the briquettes. The fine anthracite has a 5% ash content, and one half thereof consists of aluminum silicates. A mixture is made of 2 kgs. starch made from potatoes and kg. sodium borate. This mixture is added to and worked in a dry state through the duff. Then about 4 kgs.

of water is added (the amount of water depends on the percentage of water already contained in the material to be moulded), and the mass is kneaded. The thus-obtained slurry is heated, preferably by means of hot air or hot gases (combustion gases). After this, the mass is pressed to form briquettes in a roller-press.

What I claim is.

1. Method of producing smokeless, solid fuel briquettes of low ash content from crushed or powdered solid non-bituminous fuel, the ash of which contains approximately 50% of aluminum silicates, comprising adding suflicient aluminum silicates to the fuel to bring the total quantity of aluminum silicates to approximately 2 of the amount of fuel, mixing the crushed fuel with approximately 2% of an amylaceous binder in a dry pulverulent state, said binder containing an alkaline-boron salt in the approximate ratio of-l part of salt to 5 parts of the total quantity of aluminum silicates present, adding water, heating the mass, kneading the same, and pressing it into briquettes, the said quantity of alkaline-boron salt and aluminum silicates being just sufficient to form, at the temperature of combustion, a coherent n0n s1agging skeleton in the briquette.

2. A smokeless fuel briquette of low ash content which is coherent even during burning, comprising a shaped and pressed product of approximately 100'parts of non-bituminous fuel duff of low ash content, aluminum silicates present, consisting at least in part of the aluminum silicates of the said duff, andconsisting in total amount of approximately 2 /2% by weight of the amount of dufi present, approximately 2% of an amylaceous binder, and an alkaline-boron salt present in the approximate ratio of 1 part of salt to 5 parts of aluminum silicates, the salt and silicates thus being present in just suflicient quantity to react at the temperature of combustion of the briquette, to produce a non-slagging skeleton in the briquette sufficiently'strong to prevent the briquette from disintegrating during combustion.

LEENDERT JOHANNES JACOBUS HAZELZET.