Guizhou, a province situated in the southwest of China, is renowned for its mountainous terrain. Historically, the unique landscape posed challenges to transportation before the era of modern infrastructure projects in China, making travel to and from the region exceptionally challenging. Despite these difficulties, Guizhou’s terrain also harbours valuable resources, with coal being a particularly significant asset for the region. Back in 1885, Guizhou Governor Pan Wei reported to the Qing court: “Guizhou is barren and poor; all areas are mountainous, although it is rich in mineral resources, especially coal and iron.”
In 1996, Guizhou reported that over 40% of the province’s total land area had mine-able coal resources. Of the 86 counties, 74 produced coal. Back then, only 10% of the coal resources were being excavated and utilised. To unlock the full economic potential of Guizhou’s coal mines, many, including Guizhou Guineng Investment Stock Co Ltd. have resorted to giving their mines a ‘technical’ upgrade. In 2020, Guineng’s Deputy General Manager, Hongdeng Qiu, stated: “Beginning this year, we will vigorously promote the innovation and application of artificial intelligent equipment and technology, especially integrating the Internet, big data, and coal mining technology.”
With the aim of revolutionising the coal beneficiation process, increasing coal production, and reducing environmental pollution, Guineng decided to collaborate with HPY Technology and utilise its Golden Coal Series dry coal sorter at their Hebian Coal Mine, located in the city of Liupanshui, Shuicheng county. In 2020, the mine’s annual coal production capacity was only 300,000 t. According to the mine’s Electromechanical Deputy Manager Mr Li, the mine has now increased its throughput to 600,000 t per year.
Before adopting HPY’s dry coal sorting machine, Hebian mine after extracting coal from underground used a large amount of water and various chemicals for coal sorting. This has been known as the ‘wet’ coal preparation method, which is also the most prevalent process used for sorting coal and gangue in the industry. Not only flotation and dense medium cyclone plants need to be built using this method. It also means that the mine needs to build a special treatment facility to deal with the wastewater afterward, incurring additional expenses and higher demands for process water. With HPY’s dry coal sorting method, the process flow occupies significantly less space, is easy to assemble and operate, and conserves water resources.
The mine opted for a 1.6 m wide Golden Coal Series dry coal sorter, directly placed next to the underground mining site to reject the gangue using the machine. After the raw coal is mined, it is then hoisted up from underground to the surface, and then gets transported via a belt to the coal processing plant nearby. Situated at the top of the coal processing plant, the HPY Technology’s Golden Coal Series employs X-ray transmission (XRT) detection to sort coal from gangue by exploiting the distinctive density and atomic number characteristics.
The X-ray source emits rays through the material, and the X-ray detection system on the opposite side measures attenuation. Computer analysis, using algorithms, distinguishes coal from gangue based on X-ray attenuation profiles. The computer’s instructions then facilitate a sorting mechanism to efficiently separate coal and gangue streams, ensuring precise material sorting. The Golden Coal Series in the Hebian mine, can sort a particle size range of +40-300 mm; reach a processing capacity of 180-200 t/h; produce a coal content in the gangue of ≤ 1%; reject more than 95% of the gangue; and increase the calorific value from 2,000 kcal/kg to 4,000 kcal/kg. By eliminating the gangue in coal, HPY’s Golden Coal Series eliminates a significant cost associated with the original wet washing system. The sorted coal is subsequently transported by trucks for commercial distribution in the market.
When asked about the present issues that many of the mining plant faces, Mr Li stated: “For many coal mine owners nowadays, because of the coal quality requirements, big coal mines have built complex coal washing plants – ordinary coal mines don’t even have them. The disadvantage is that it comes with high water usage, and it needs more equipment, leading to higher capital investments and use of more operating space. The investment period and costs are longer and larger. It also requires a matching wastewater treatment system.” He noted there are many requirements for environmental protection that one needs to be mindful of.
In Hebian Coal Mine, HPY Technology helps save transportation and flotation costs to the tune of approximately US$770,000 per year. Currently, the company is still conducting tests on the second generation of the Golden Coal Series and says it has made a breakthrough with the sorting air jets, reducing maintenance time and according to HPY will make it the longest-lasting sorting machine of its kind in the industry.