Project Background & Pain Points

The turbid circulating water system of a west coast aluminum smelter in South Africa has total flow rate of 2400m³/h, cooling electrolytic cells and hot rolling mills. Water contains massive alumina dust, iron oxide scale and sediment. Old bag filters without automatic backwash clog easily, requiring full water shutdown for bag replacement every 48 hours for 6 hours each time, bringing huge output losses from electrolytic cell load reduction. Two full-time maintenance staff disassemble bags and clean filter chambers round-the-clock with monthly bag procurement cost over 12,000 Rand. Manual flushing consumes massive water; the water-scarce local area imposes environmental penalties for excessive water use.Fine dust penetrates bags and accumulates in heat exchanger channels, lowering heat exchange efficiency and raising boiler fuel consumption by 11%. Without online differential pressure monitoring, sudden full blockage easily causes pipeline overpressure and leakage risks. Client core demands: fully automatic multi-chamber online backwash, uninterrupted water supply, in-situ replacement of old equipment and sharp reduction of labor & consumable costs.

Customized LEFILTER Solution

Aiming at high-dust large-flow smelting conditions, 4 sets of LF-FC multi-chamber backwash filters are installed in parallel on the main circulating water pipe. The whole machine adopts 304 stainless steel cylinder with 200μm wedge screens to intercept alumina fine powder and iron rust. Independent reverse washing structure for separated chambers: single chamber backwash activates automatically when differential pressure hits 0.13MPa while other chambers keep filtering. The full reverse washing & blowdown process takes only 30 seconds without interrupting turbid circulating water supply.Equipped with local English PLC intelligent control cabinet and high-precision differential pressure sensors, supporting dual backwash triggers of differential pressure & timing. Reserved Modbus communication interface seamlessly connects to smelter DCS central control platform for remote viewing of inlet & outlet differential pressure, backwash frequency and total blowdown volume, remote cleaning threshold adjustment and acousto-optic fault alarm.Standard flanged ports match original pipelines 1:1 without large-scale civil reconstruction. Supported by 24-hour full-load production capacity, full equipment completes anti-corrosion processing, factory inspection and ocean delivery within 9 days to meet the smelter’s urgent technical transformation schedule.

Differentiated Core Advantages

1. Independent online backwash for separated chambers ensures uninterrupted water supply during single-chamber cleaning to realize 24-hour non-stop electrolytic smelting and eliminate output loss from bag replacement shutdown;

2. Fully automatic differential pressure triggered reverse washing thoroughly strips screen impurities, completely removing manual bag disassembly and cutting maintenance workload by 82%;

3. Integrated reusable wedge metal screens replace disposable filter bags, slashing annual consumable procurement cost by 90%;

4. Backwash only uses clean filtered circulating water with consumption only 38% of old bag filters, lowering factory water intake and complying with South African water-saving regulations;

5. Stainless steel anti-corrosion cylinder adapts to high-dust, humid acid & alkali smelting water environment with service life over 12 years.

   
   

Operating Effects & Client Benefits

Stable operation for 13 months. Maximum influent suspended solids reach 160mg/L with effluent stably controlled ≤8mg/L. Heat exchanger blockage frequency drops by 91%, cleaning cycle extends from 45 days to 90 days, cutting annual smelting shutdown output loss by 6.2 million Rand. Automatic backwash eliminates full-time bag replacement posts, reducing maintenance staff from 2 to 1 and saving 360,000 Rand labor cost yearly. The plant saves 101,000 tons industrial circulating water annually and avoids water overuse penalties.Smooth pipelines restore heat exchange efficiency, cutting boiler fuel consumption by 10% and saving fuel procurement equivalent to 780,000 RMB yearly. This backwash filter achieves multiple goals of stable production, water saving and low consumable cost, serving as a benchmark turbid water filtration renovation case for non-ferrous metal smelting in Africa.