Enhancement of coal slime by means of complying with the environmental regulations coal upgrading & burning processes

Aim: exploit coal slimes by adapting preparation techniques
for improved combustion in mechanically-stoked boilers,
direct combustion in fluidised bed boilers. New coal-oil-
water fuels will be developed.

Objective of the project Development of efficient and complying with environmental regulations utilisation technologies for coal slime from the mining industry. Upgrading of substitute fuels. Background In POLAND, a rising problem with accumulation of coal slime requires rational solutions. Besides occupying the vast storage areas (stocks, tailings), coal slime generates a clear threat to the environment (dust, leakage). Preliminary data show that the annual production of coal slime amounts to approximately 5.5 million tonnes while the capacity of already stored slime reaches 16 million tonnes where the ash content is 40-65%. The properties of the coal slime available in the Silesia region (fineness, high ash content) prevent conventional technologies from being applied. Additionally, the economy of coal preparation plants aiming at the production of higher quality solid fuels as well as the technological application of coal upgrading processes such as flotation contribute to increasing the amount of already existing coal slime. To solve the problems mentioned above, the development of technologies enabling transformation of coal slime into upgraded fuels permitting their utilisation in existing burner equipment is required. Additionally, the composition and properties of these fuels should be such that they comply with environmental protection requirements and operational costs should be adjusted to the economic conditions prevailing in Central European countries. Project organisation The project will consist of two phases: - Research, development and pilot testing of various efficient coal slime enhancement technologies followed by commercial and pilot plant assessment trials of the resulting substitute fuel in existing burner equipment. - development of modular enahncement equipment adapted to various conditions prevailing in mining industries of Central European countries, and more specifically in POLAND. A. Phase 1: Phase 1 aims at the design and development of several methods for the enhancement of coal slime that will be assessed on pilot scale equipment. It includes three parallel approaches to commercially exploit coal slime: - the first one concerns the blending of coal slime with other components followed by granulation treatments in order to obtain fuels which can be burnt in existing burner equipment based on a mechanical stoker - the second one involves the development of direct coal slime combustion methods in adapted burning equipment e.g. fluidised bed boilers - the third one consists of using selective oil agglomeration as a coal slime enrichment technique followed by: * the preparation of coal-oil-water slurry and its combustion in adapted combustion equipment i.e. fluidised bed boilers and pulverised fuel boilers * granulation and combustion in mechanical stoker boilers. Testing plants will be equipped with the appropriate instruments to measure and further control emissions from combustion of produced fuels. The produced fuels will be tested on commercial scale burner equipment. The most promising technology, resulting from the research and development stage, will be selected and solutions for modular design, adjusted to various conditions, will be researched and economically assessed in the second phase. 1. Preparation of coal slime for combustion in mechanical stoker boilers. This method of coal slime utilisation will consist of the following processes: - mixing in appropriate ratios with fine steam coal and fine coking coal - granulation with addition of binder and modifiers of combustion - curing. Mechanical stoker boilers still exist in most of Central European mines, substitute fuels, manufactured from coal slime, could be thus utilised on site and excess amounts sold to outside clients. As the result of the above process the boiler is fed by appropriate fuel complying with size, distribution and emission requirements. The R & D tasks of this part of the project will consist of: - determination of components ratios in granulation mixture - determination of granulation procedure - drawing up of drying conditions - testing of combustion and emission behaviour 2. Direct combustion of coal slime Direct combustion is a promising way to utilise coal slime. This technology should be, however, considered with a view of application for fluidised bed boilers, because of their flexibility as ragards fuel quality and composition. This part of the project includes investigations into the following unit processes: - coal slime preparation and transportation - feeding into a boiler - combustion and emission control. The need to draw up the above-mentioned processes is mainly due to the unfavourable properties of coal slime. Among them high content of ash and water should be listed. The feeding into the boiler will be viewed either with the coal slime as it is, or with a coal-slime-water slurry preparation. Implementation of the results could be done by retrofitting an existing boiler into fluidised bed boiler. 3. Selective agglomeration Amongst the physical processes, the selective oil agglomeration is one of the most relevant techniques for the enhancement of coal. Up-to-date research shows the possibility of 80-90% efficiency of coal demineralisation. The principle of selective agglomeration is based on the recovery of carbonaceous particles from water suspension by means of hydrophobic oil phase and concentration of mineral matter in the water phase. Selective agglomeration makes it possible to use various types of agglomerating agents (diesel, various oils, light hydrocarbons, etc.). We intend to apply, as upgrating process of coal slime, the selective agglomeration process and to develop feasible techniques for commercially exploiting the product, i.e. preparation of coal-oil-water slurry and its combustion in adapted combustion equipment i.e. fluidised bed boiler and pulverised fuel boiler and combustion in a mechanical stoker boiler after a granulation step. The parameters of selective agglomeration that should be determined are: * the properties of coal slime and oils, * condition and time of mixing, * share of oil, and * pulp density. The utilisation of waste oils would be an advantage of the process, increasing its cost effectiveness by reducing production costs. This part of the project will consist of two stages: (a) selective oil agglomeration research and development: * preliminary research for selection of coal slime to be upgraded and appropriate oils * determination of optimum parameters * determination of production costs * determination of process flexibility to changes in raw material properties. (b) development of product application technique preparation of coal-oil-water slurry: * determination of: - an optimum coal size distribution - the optimum coal/water ratio, the type and quantity of dispersants to be added - mixing conditions * tests of combustion in adapted fluidised bed boilers and pulverised fuel boilers: - construction or modification of injection equipment - determination of efficiency and emission - granulation and combustion in mechanical stoker boiler * determination of granulation procedure * testing of combustion and emission behaviour 2. Phase 2 Phase 2 is directed to designing of modular technological concepts adapted to various conditions and material properties existing in mining industries of Central European countries and performing a feasibility and economic study in order to prepare the commercial application strategy. The commercial exploitation will require specific funding (from within other European programmes, by international financial institutions, government funds or private funds or mining industries). Solutions for modular design, adjusted to various conditions in Central Europe, will be assessed. The project will be carried out through the collaboration of three Polish and one Belgian participant. Two of them represent research centres, one is a private agency and one is an industrial company. The project is expected to last 36 months, starting on 1st July, 1996.
Project ID: 
1 570
Start date: 
Project Duration: 
Project costs: 
600 000.00€
Technological Area: 
Market Area: 

Raising the productivity and competitiveness of European businesses through technology. Boosting national economies on the international market, and strengthening the basis for sustainable prosperity and employment.