China Nonferrous Metallurgy

In view of large amount of nickel-containing solid waste stockpiling and high energy consumption and cost of the existing technology, the paper makes use of strong viscosity of iron-containing red mud, carries out pelletizing it with nickel containing sludge, and solid medium high temperature direct reduction-grinding magnetic separation process to extract ferronickel , and conducts the test according to the orthogonal method L9 (34) with four factors and three levels, and draws the following conclusions. It is feasible to extract ferronickel from iron-containing red mud and nickel-containing sludge by synergistic reduction after pelletizing. The optimum process parameters are as follows: coal blending ratio 4%, roasting temperature 1150℃, roasting time 45min, and grinding time 30 min; under the above conditions, the nickel grade of ferronickel powder is above 75.00%, ferronickel grade is above 93.00%, and ferronickel recovery is above 80.00%. According to 95% grade correction, the material cost is below 475RMB/t, energy consumption below 712kgce/t and CO₂ emission below 0.99t/t. In the test, it was found that the factors affecting the cost of ferronickel extraction process materials, energy consumption and CO₂ emissions were changed in the weakening order: coal blending ratio, roasting temperature, grinding time and roasting time. Compared with the existing nickel-containing solid waste treatment process, this process not only realizes the extraction and utilization of ferronickel from nickel-containing sludge and iron-containing red mud under the conditions of low energy consumption and low emission, but also reduces the stacking of solid waste. The ferronickel alloy produced can be used for steel enterprises to produce high value-added stainless steel. The main components of the remaining oxides after reduction are SiO₂, Al₂O₃ CaO and MgO, which can be used to produce cement raw materials.