Applicability of a Dense-Medium Cyclone and Vorsyl Separator for Upgrading Non-Coking Coal Fines for Use as a Blast Furnace Injection Fuel

Abstract

Replacement of metallurgical coke by high injection rates of thermal coal into the blast furnace is an important technology as it reduces the cost of hot metals significantly. However, one of the main problems that prevents the use of thermal coals is their high mineral-matter contents. Although, the ash content of coals to be injected in a blast furnace should be as low as possible, a maximum of 16% ash is acceptable. A non-coking coal sample from Chhattisgarh area, India, having a feed ash content of around 27% was collected for beneficiation studies to a grade acceptable for the injection purposes. A series of experiments were conducted in a 76-mm diameter dense-medium cyclone (DMC) and a Vorsyl separator (VS). It is observed that a clean coal having around 16% ash can be produced using both the cyclones if the variables are properly optimized. Further, it is observed that at the same ash level the yield of clean coal was 5%–6% more in VS than in DMC. It has also been demonstrated that at the same ash level, the magnetite medium stability in a VS was better than a DMC.