Main Trends In Russian Coal Preparation Development
Separation and treatment of fine coals remain the “bottlenecks” of the coal preparation technology.
In recent years the most common items of equipment used for dewatering have been high-frequency screens, settling and filtering centrifuges, belt press-filters, continuous disc filters operating under pressure. In flow sheets selection a clear trend can be observed to maximum use of mechanical methods of dewatering and reduction of the share of thermal dewatering, and even full omission of drying processes in a number of cases (Table 1). However, it should be noted, that the problem of use of high-efficient settling and filtering centrifuges requires an extremely careful technical and economical justification.
The plants under construction and those being retrofitted are furnished both with Russian (screens, crushers, heavy media separators and cyclones, regeneration separators, flotation machines etc. ), and foreign equipment, especially for processes of cleaning and dewatering of coarse and fine slimes (spiral separators, high frequency screens, screens for dry sizing of fine fractions, belt press-filters, heavy-media cyclones, settling and filtering centrifuges, continuous disc filters operating under pressure, etc. ).
At new plants, due to the application of advanced technology and high performance equipment the loss of combustible mass and environmental impact are reduced, cost and time of construction are cut down, working conditions of attending personnel are improved.
To obtain marketable products from poor-structured coals, undersized thermal coals and slimes the techniques and processes of briquetting have been developed and high-performance up-to-date briquetting plants have been built.
The main trends in coal preparation development are
- enhancement of coal preparation effectiveness;
- optimization of coal preparation flow sheets taking into consideration the nature of coals to be cleaned;
- development of energy-saving technology and equipment to produce both granular and briquetted enriched power-plant fuel from low rank coals and secondary coal resources;
- reduction of harmful environmental effects of coal preparation processes;
- development of technologies of integrated processing of brown coals into target products.
In this context, the main directions of R&D are the following:
- study of sliming processes and development of effective methods of slime processing, dewatering and utilization;
- study of mechanisms of interaction of fine coal-mineral particles with flotation reagents and flocculants to step up their separation process;
- study of nature and structure of coals to control consumer’s effect of marketable products produced by coal preparation.
All above mentioned issues relative to the development of coal preparation technology and equipment, designing and operation of high-efficient coal preparation plants, trends in R&D are outlined in the papers of Russian coal preparation specialists.