Coal washing

GRAVICON SPE designs and supplies "turnkey" modular preparation complexes for washing power generating, coking and anthracitic coals with a capacity of 25-400 t/h. This is an analogue of a full-featured Preparation Plant (PP) with lower capital expenditures and preparation costs, fully closed water-slurry circuit and tight implementation time.

Project implementation period is 6-8 months

Complex operating personnel is 4-5 men per shift

Energy consumption is 1.2 kWh per ton of initial product

Water sedimentation tank volume is 2х300…500 m3

 Among all common methods for coal preparation (hydraulic jigging, flotation, dense-media preparation and pneumatic separation), jigging exclusively dominates by cluster of features (preparation costs, environmental compatibility, capital expenditures, quality of concentrate, in-use simplicity) in the industry sector as far as concerned creating new modular complexes at sites of coal mining or replacing obsolete worn-out models.

Comparison with alternative technologies:

Flotation: used if there is a need for preparation of a large amount of size "minus" 0.5 mm and below. Capital expenditures are 5-7 times higher, preparation cost is 2-3 times higher, application of chemical agents (including toxic and flammable, which are necessary (a) to buy, (b) to store, (c) they fall into the circulating water, causing environmental pollution), high demands for attending personnel qualification, expensive and wearing out control system components (flow meters, densitometers etc.), area of preparation site (with manifolds) is 3-4 times larger, inability of outdoor installation. An expensive, environmentally unfriendly technology, which, however, is effective in the preparation of a large number of micron sizes. GRAVICON SPE, being an inheritor and successor of achievements of GIPROMASHUGLEOBOGASHENIE Institute in terms of gravity separation, supplies MFU series flotation machines complete with control system and chemical agents feeding >>>>>>>

Heavy media: preparation cost is 3-4 times higher due to the larger number of attending personnel (up to 15 men per shift), substantially greater energy consumption (4...5 kW per ton of initial product), need to regularly purchase magnetite, as up to 4 kg is used with each ton of rock and concentrate. Circulating water is not clean, but contaminated with a weighting agent and the requirements for quality of circulating water clarification are substantially higher than in jigging. Based on the aforesaid, payback periods of projects are long and take up to 3-4 years. Moreover, during periods of reduced coal prices, the production cost of the power-generating coal concentrate is even close to its market price.

 Pneumatic separation: indispensable when there is no water at all, even 5 m3/h. It reduces ash content by 5-10% per pass, depending on the initial product. The initial product humidity should not exceed 5%. With increasing the humidity of the environment (rain, snow) or material, the separation degrades in quality or takes no place at all. The presence of clay is not allowed (for jigging, the presence of clay up to 15...20% is generally not a problem even without the use of additional mechanisms (such as trommels and their analogues) in

the head of an engineering process). Expensive, large-format aspiration system, complications of storage, transportation, disposal of large amount of fine dust. Inability to obtain low ash concentrate. Honest manufacturers of this type of equipment no longer call it "preparation equipment", but use the term “equipment for preliminary cleaning of rock”, which fairly presents its functionality. Moreover, in dry hot environments, it is desirable to comply with critical requirements for the moisture content of initial raw material.

If in the course of jigging under strict moisture requirements for concentrate, only the concentrate itself requires dehydration/drying, then during pneumatic separation it is necessary to dry the entire initial product, in order to ensure year-round operation, including periods of high humidity.

GRAVICON SPE, following traditions of Preparation Machines Department of the GIPROMASHUGLEOBOGASHENIE Institute, supplies advanced PSM series pneumatic separators for preparation of mine coals and heap >>>>>>>

Dry coal cleaning (with cyclones, vacuum) has all the disadvantages of traditional pneumatic separation including those, specifically related to this technology:

- initial product humidity should not exceed 7%, which is difficult to achieve in areas with moderate and continental climates, i.e. the separation is possible in the dry hot season only;

- high energy consumption up to 1,500 kW, which in terms of a ton of initial product is 2.5...3 times higher than that of jigging;

- very large areas of the plant (up to 5 hectares or TEN football fields). As a result, it is impossible to arrange the plant sheltering in a financially expedient way, which makes impossible its operation in severe climatic conditions;

- no intermediate product is recovered during preparation, which causes either tailing losses of useful product or increase in the ash content of concentrate;

- only narrow-classified material is processed since, in contrast to jigging, heavy media and pneumatic separation, the separation does not occur by material density, but by its weight. Jigging involves many forces acting on the material and the result of their interaction is a separation in density. This technology involves the only strictly vertical force acting on the material. Consequently, the material should be located in one layer and have (preferably) the same size. With a difference in particle size, smaller pieces of rock will have less weight than larger pieces of coal, resulting in rock penetration into the concentrate;

- materials with a large difference in density of useful material and tails are separated. Jigging indicators with 0.1 g/cm3 delta between the concentrate and rock are unobtainable for this technology;

- low capacity of 1 m2 of the conveyor working surface: good quality separation is possible only when the material is positioned in one layer or one layer and a half.

GRAVICON SPE is the developer and manufacturer of three of five possible categories of coal preparation equipment (Jigging Machines, flotation machines, pneumatic separators) and is ready to supply any of them at customer’s request. Our attitude to heavy media remains the same: the technology does not have any substantial technological advantages over jigging, either in quality or in capacity and, therefore, its economic indicators are much worse.

GRAVICOM modular preparation complexes are an alternative to the construction of traditional stationary preparation plants, providing that

- project implementation period is reduced from 1-2 years to 6-8 months;

- capital expenditures are reduced by 5-7 times;

- thanks to the optimization of the number of personnel, technological chain, energy consumption, etc., operating costs are reduced by 2-3 times compared with classic ore mining and preparation plants.

 Our complexes are successfully working on the preparation of both power-generating coal, coking coal and anthracite. The complex placement at a mine or open-cut mine can be considered as the creation of a closed cycle of marketable product production, which in addition to economic benefits substantively increases competitiveness of such a cluster as mine / open-cut mine-preparation plant.

Typically, ash content of the concentrate for our equipment is

- 12...16% for power-generating coals;

- 7...10% for coking coals;

- 4...8% for anthracites.