Coal Age Magazine - For nearly 100 years, Coal Age has been the magazine that readers can trust for guidance and insight on this important industry.
Issue link: https://coal.epubxp.com/i/131326
concentrators is becoming increasingly important, especially as the feed grade in mineral deposits is on a long-term downward trend. Both in coal and ore applications, pre-concentrating run-ofmine coal and ore streams by removing waste rock can enhance concentrator performance significantly, he told Best of Germany, with the company's sorters "acting as an interface between the mine and the concentrator." Steinert reports that there are now several operations worldwide that are either using its sensor-sorting equipment, or are currently in the process of testing it. As an example, the company's XSS-T X-ray transmission technology has proved to be very effective as a sorting system in both the coal and metal ore industries, Krehla said. The X-ray technology penetrates the run-of-mine material, with the different levels of absorption of each group of elements within the ore acting as the sorting criterion. For instance, ore minerals may have a higher density—and therefore a higher absorption of X-rays—than barren rock, allowing the two to be differentiated. In one application, a tungsten mine in Western Australia is using an XSS-T system on screened run-of-mine ore to upgrade it from 0.2% to 6% tungsten in one pass, while reducing the volume of rock by 80% and cutting demands on the subsequent milling and flotation circuits substantially. The same technology has been used to separate barren rock from diamond-bearing kimberlite, thus upgrading the diamond ore for subsequent sorting. Steinert points out, however, that uses of its X-ray sorters are by no means limited to ores but also cover coal preparation, both on run-of-mine coal and for reworking old spoil heaps that contain recoverable 2013 • VDMA MINING SUPPLEMENT coal. An operation in West Virginia that is aiming to recover hard coal from a 1950s dump will use the XSS-T as its sole sorting machine, the company told Best of Germany, with the recovered coal being of high-enough quality for use directly as power-plant fuel. This facility will start operation in early 2013 and will be the pilot plant for a number of others, Steinert added. In cases where density difference is not big enough for X-ray separation, the company produces systems based on the recognition of optical features such as color, shape and surface structure, or by detecting electric conductivity. And, Steinert says, using different combinations of sensors in one machine enables it to detect and evaluate many mineral properties as a means of sorting out value from waste. VDMA The XSS X-ray sorter from Steinert. VDMA 41