Ocena opłacalności wzbogacania węgla w układach osadzarek

Coal preparation processes have a decisive impact on sales of commercial products. Obtaining the maximum production value from raw coal at different commercial contracts is an important issue. It is therefore important to search for new ways of increasing the production value.

Jigs partition curves have a shape deviating from the ideal curve, which causes the appearance of incorrect grains in the process of coal enrichment. Application of a group of jigs improves the shape of the resultant partition curve. With the same demanded value of ash content in the final concentrate from a group of two jigs (Fig. 3) with the repeated concentrate enrichment (2 os. K) and with the recirculation of intermediate product (2 os. rec. KO), it is possible to significantly increase the production value when compared to the case of a single jig – particularly in the case of a demanded low value of ash content.

Estimating the increase in operating costs (investment costs have been omitted as irrelevant per 1 Mg al enriched coal over the second jig lifetime) shows that – particularly in the case of a low demanded value of ash content – application of the second jig can remain economically profitable (Fig. 5). Thus, if the coal preparation plant has more jigs, the advisable action is their suitable use through the application of secondary enrichment or intermediate product recirculating.

When the jig has too low productivity relative to the amount of the raw coal, the enrichment is performed using two or three jigs (3 os. system in Fig. 6a). In the case of different raw coal feed size classes, jig partition curves have different shapes (Fig. 2), so the cleaning effects are different in individual grain size classes. For this reason, it is advisable to enrich coal in the parallel arrangement with separation of grain size classes (system 3 os. kl in Fig. 6b), i.e. with initial classification. In this case it is possible to select partition densities for individual jigs to maximize the desired quality concentrate yield. In this way, the production value can be maximized. This value is higher than in the case of the reference arrangement (3 os.), particularly at a low demanded ash content value and in the case of hardly-washable raw coal feed.

With jig-systems it is possible to obtain a lower minimum desired ash content in concentrate than in the case of the reference arrangements (1 os. or 3 os.)

This paper, concerning issues of repeated enrichment (secondary without recirculation and with recirculation of an intermediate product), supports the trend of demanded improvement of enrichment methods. Analysis of jig cleaning systems should be particularly important in the case of design or upgrading tasks in coal preparation plants.