Waste gangue represents a headache for all coal mines – it contaminates product, wastes hoisting capability, and piles up on the floor as an environmental legal responsibility.
Yangcheng Coal Mine in Shandong, China, confronted a fair higher problem. Uncooked coal ash content material reached 42.08%, and roughly 4 Mt of coal reserves have been trapped beneath floor buildings – unrecoverable by typical strategies. The mine produces 350,000-400,000 t of gangue yearly, straining the primary shaft and creating mud, leachate air pollution, and land occupation.
The standard answer could be to hoist it up and dump it. Nevertheless, MeiTeng Expertise, along with Haina Expertise and China College of Mining and Expertise, took a very totally different method – one which retains the whole lot underground in a closed-loop system.
The answer was a completely underground built-in sorting and backfilling system. MeiTeng designed a personalized underground clever sorting with longwall panel-by-panel cemented backfilling answer for Yangcheng. Building started in early 2024 and the system entered service in December 2024.
On the core of the system is an underground XRT clever dry sorter, which makes use of X-ray and optical recognition to separate coal from gangue within the 300-400 mm measurement vary. Key efficiency indicators embrace a gangue rejection fee of ≥90% and coal loss in reject of ≤3%.
The separated gangue by no means goes to the floor – it’s immediately fed into the backfilling course of underground. The system consists of a floor slurry preparation station and an underground backfilling system.
On the floor station the combination design has a 78.5% focus, with 50% gangue solids, 9% cement and 20% fly ash. The capability is 100 m³/h, with supply by way of two slurry boreholes and one materials feed borehole (339 m deep).
For the underground system, key gear features a high-fineness crusher (gangue to <10 mm), steady mixer and backfill industrial pump, with a system capability of 150 m³/h.
Yangcheng Mine applies longwall panel-by-panel cemented backfilling in a 7.8 m thick coal seam. The mining space is split into strip roadways, with a ‘mine one – backfill one’ cycle. The backfill slurry undergoes three curing phases: preliminary setting (4–6 hours) when it develops preliminary energy; curing (approx. 24 hours) when it features important compressive energy; then stabilisation (roughly 7 days) when it achieves design energy (>90% compaction).
Since January 2025, about 650,000 t of beforehand stranded coal has been unlocked and 470,000 t of high-quality coal extracted. The system consumes over 300,000 t of gangue yearly, together with fly ash (150 t/d) and slag from the mine’s energy plant – eliminating floor stockpiles and their ecological dangers.
When it comes to financial advantages, Wang Xukui, Deputy Common Supervisor and Chief Engineer of Yangcheng Mine says the system has added annual income of US$45 million, with the mine life prolonged by 11 years. In 2025 alone the worth created was US$20.5 million, with a 2026 goal of 600,000 t of backfill mining.
In September 2025, the undertaking was chosen for the Nationwide Coal Mine Backfilling Mining Superior Applied sciences and Sensible Case Assortment, recognised as a replicable benchmark for inexperienced and clever transformation. It was additionally featured by China Coal Information on July 25, 2026.
Since 2018, MeiTeng Expertise has constructed over 30 underground XRT sorting and backfilling programs throughout China and Central Asia, masking numerous geological situations and mining operations.
