Improved Economic Method for the Utilization of Wastes from Coal Extraction in Poland

Summary

The paper deals with problems connected with utilization of wastes from coal extraction by using the Haldex method, one of whose elements is recuperation of the coal contained in waste. The large coal output in the Upper Silesian Coal Basin amounting actually to about 200 mln tons per year is the reason for the serious concern about waste treatment and related problems. These problems are aggravated by the considerable urbanization of this basin, preventing the formation of waste dumps.

The Haldex method used for many years in a joint Polish-Hungarian enterprise aims at recovery of coal left in waste and utilization of the raw material remaining after coal recovery. The process consists of separating from coal incidental materials such as metal scrap, wood, etc., and breaking them to a grain size of less than 30 mm. The wastes of this grain size are submitted to a concentration process in hydrocyclones of 500 mnuof diameter in a heavy medium suspension. The specific gravity of 1. 30-1. 35 g/cm of the heavy medium is increased by circulation of the finest grains of the raw material without any outside addition of filler up to the required level. The effective specific gravity of separation in hydrocyclones is in the range of 1.7-1.8 g/cm³.

The concentration products, i.e., coal and shale, are then drained and classified according to the needs of particular groups.

The amounts and quality of coal recovered in the process varies depending on the properties of the processed raw material; the actual recovery of coal of about 5,000 kcal/kg of calorific value is about 6.0 per cent.

The shale removed in the process is utilized for the following purposes:

• - stowing mixture to replace the traditionally used sand;

• - as raw material for production of clinker;

• - production of red ceramics;

• - production of the light aggregate, so-called shale-porite.

The production of building materials with shale recovered by the Haldex method results in great energy savings, since it allows a reduction in the use of coal, mazout or gas used previously.

The utilization of waste is realized in central plants of 3,300 to 5,000 tons per day of capacity supplied from a few neighbouring mines.

The total amount of waste processed by the aforementioned method is actually about 5.5 mln. tons per year.