DE1179181B - Process for the production of low-smoke briquettes - Google Patents

Description

Method of Making Low Smoke Briquettes The invention relates to a process for the production of low-smoke briquettes, in particular egg briquettes, by adding a lean fuel or a lean fuel mixture with a binder mixed and the mixture is pressed into briquettes.

These briquettes come in terms of strength, smoke and Dimensional stability when burned is almost the same as that of anthracite.

For the production of fuel briquettes, pitch or asphalt bitumen is usually used as a binder in an amount of 4 to 8 % . This has the disadvantage that these briquettes smoke heavily when burned and disintegrate too quickly due to the softening of the binding agent.

Instead of pitch or asphalt bitumen, there are already many other binders has been proposed among them synthetic resins. However, none of these binders have Can find wide application because either the price was too high or the quality of the briquette did not meet expectations.

It has now been found that excellent briquettes can be produced if a lean fuel or a lean fuel mixture with the addition of a small amount, not more than 4 % of the fuel weight, of one or more solid polymers and / or copolymers of olefinic hydrocarbons as binders are pressed into briquettes. Examples include: polyethylene, polypropylene, polybutylene, polystyrene or mixtures thereof, or copolymers of such substances as copolymers of ethylene and propylene, ethylene and butylene, propylene and butylene, butadiene and styrene. In most cases, an amount of binder of only 1 to 2% is sufficient, so that there are no economic objections to the high price of such a binder compared to pitch.

The fuel to be pressed need not be particularly fine; Good results have already been achieved with normal briquetting charcoal, the particles of which are smaller than 3 mm and whose grain distribution is normal and regular (50 % > 1 mm, 90 %> 0.1 mm).

The invention is explained on the basis of the following exemplary embodiments.

Example 1 1 kg of polystyrene in the form of a toluene solution was added in a mixing screw to a fuel mixture consisting of 95 kg of lean coal and 5 kg of fatty coal. The mass obtained in this way was cold-pressed at a pressure of 300 atm.

From the so formed moldings of about. 25 g was subsequently The toluene was excreted in a stream of hot air. The briquettes were a print of 75 kg and did not disintegrate during incineration.

Example II The coal mixture mentioned in Example 1 was in a Mixing screw 11 /, 0 / "polyethylene with a melt index of 7 (according to ASTM standard D 1238 T Test condition E) added in the form of fine grains <100.

The mixture was heated up to 220 ° C. in a kneading machine and then pressed at this temperature under a pressure of 700 at.

The briquettes of about 25 g could withstand a pressure of 70 kg and did not disintegrate during combustion.

A prerequisite for polyethylene is that this substance is heated when it is heated can be easily distributed in the fuel mixture. The melt index of polyethylene can therefore 1 to 20, but preferably 3 to 10, are.

Different forms of the method according to the invention are possible. So instead of a styrene solution an aqueous suspension of styrene can be applied as a binder, while the pressing pressure in cold pressing of with Styrene to bond coal particles depending on the moisture content of the mixture can fluctuate. A certain moisture content belongs to a certain optimal moisture content Press pressure. Mixtures with 5 to 8% moisture at pressures can be used without hesitation from 400 to 200 kg / cm2 can be pressed.

The disadvantage of using polystyrene in the form of an aqueous suspension is that the compressive strength of the resulting moldings even after drying does not reach a high value, while when using polystyrene in the form of a solution, However, this results in a much better compressive strength, the relatively high one Price of solvents such as benzene, toluene, xylene, as a serious disadvantage is to be seen because in this process a large amount of solvent as a result of the high volatility of these solvents is lost through evaporation.

The solvent can hardly be recovered industrially.

It has also been found that by using polystyrene as a binder, namely in the form of an aqueous suspension, fuel moldings with excellent compressive strength are obtained if a little tar oil distillate is added to the molding compound, which goes over at atmospheric pressure between 130 and 300 ° C and after the briquetting process is driven out again by heating. The so-called "wash oil" fraction, which passes over when tar oil is distilled between 230 and 300 ° C, and the so-called "coumarone oil" fraction, which distills over when tar oil is heated to between 140 and 200 ° C, are mentioned here as very suitable tar oil distillates. The addition of tar oil distillate has such an effect on the polystyrene emulsion that a kind of skin is formed, as a result of which the polystyrene emulsion is now better distributed over the particles to be briquetted and part of the tar oil distillate is retained by the polystyrene, even after briquetting and removal of the tar oil distillate by heating will; the binding capacity of the polystyrene is thereby largely improved.

From the test results compiled in the table the beneficial effect of adding tar oil distillate. The experiments found in such a way that the fuel mixture to be briquetted is 90 percent by weight consisted of lean coal and 10 percent by weight of fatty coal, polystyrene in In the form of a suspension with 300/0 water was added.

While the fuel was mixed with the aqueous suspension 0 to 3% tar oil distillate, based on the amount of fuel, added, whereupon @reknetet until a homogeneous mixture was formed; then the Mass briquetted at 300 at, after which the resulting briquettes with a weight of about 25g at 150 to 200 ° C were dried.

To compare the compressive strengths, the table mentions a few tests according to which so much benzene was added to the molding compound that the polystyrene initially added dry dissolved in it during the kneading process. Adding more than 5% tar oil distillate is of no use, since in this case the associated costs - if the tar oil distillate is not recovered during drying - are too high. If, on the other hand, the tar oil distillate is recovered, the same technical difficulties have to be dealt with as in the recovery of the benzene homologues. Polystyrene tar oil distillate in percent by weight in percent by weight the amount of to the amount of to be printed briquetting briquetting strength Fuel. Fuel in kg Polystyrene is added in the form of a suspension washing oil coumarone with 300.1 " water oil 0.5 I 24 0.75 3 65 1 0.5 13 1 I 57 1 2 65 1 2 74 1 3 98 1.25 1 65 1.5 10 1.5 0.5 34 1.5 0.5 45 1.5 1 51 1.5 I 88 1.5 1.5 74 1.5 2 104 1.5 2 105 Dry polystyrene benzene printing in percent by weight in percent by weight strength of the fuel of the fuel in kg 1 20 60 1.25 22 78 1.5 24 137

Claims (4)

Claims: 1. Process for the production of low-smoke briquettes, in particular egg briquettes, made from lean fine coal or a lean fuel mixture with the addition of a binder from the plastics group, characterized in that as a binder, one or more solid polymers and / or copolymers of olefinic Added hydrocarbons in an amount not exceeding 4% of the fuel weight will. 2. The method according to claim 1, characterized in that as a binder Polystyrene is used and the mixture to be briquetted is cold-pressed. 3. Procedure according to claim 2, characterized in that the mixture to be briquetted the distillation of tar oil between 130 and 300 ° C obtained ter oil distillate in added in an amount of a maximum of 5% and expelled by heating after briquetting will. 4. The method according to claim 1, characterized in that the binder Polyethylene used with a melt index from 1 to 20 and that to be briquetted Mixture is hot-pressed.