Comprehensive Utilization Of Jin Chuan Nickel Slag

Nickel slag is a solid waste with Fe O.Si O2 as a main component, which is generated in the smelting process of nickel. More than 40 million tons nickel slag have been stockpiled in China according to statistics, and about 2 million tons of waste residue increases annually. There are many kinds of metals in the nickel slag, such as Fe, Cu, Co, Ni, etc. The contents of Fe, Si O2, Mg O and Ca O are 40% ~ 45%, 32% ~ 36%, is 1% ~ 11%, and1% ~ 3%. Nickel slag also contains varying amounts of nickel, copper, cobalt, gold, silver, selenium, cadmium, arsenic, mercury and other valuable metals, so it is seen as a huge potential recycled secondary resource However, it has not been effective utilization yet because of its mineral composition is complex. So far, most nickel slag is stockpiled, which not only takes up space but also has environmental pollution problems. Therefore, how to utilize nickel slag effective has become one of the main topics for breakthrough.For the problems existing in the comprehensive utilization of Jin Chuan nickel slag, a technical approach is put forward to carry the comprehensive utilization of iron ore and gangue. A technology by a reduction roasting which gets direct reduced iron and gelled material at the same time can achieve comprehensive utilization of all components of nickel slagReduction roasting experiments are accomplished in a controlled temperature resistance furnace. The alkalinity of reduction process can be adjusted by adding lime, which the reducer is coal. Experiments are respectively studied from the aspects of the amount of reducer, reduction temperature, reduction time, the amount of lime addition, reaction atmosphere, etc. The research results are as follows:(1) Thermodynamic calculations results show: C2 S can be generated at a low temperature; Ca3 Mg Si2O8 appeared at 850?, its exist stable area is smaller so as to 900? disappear; Al2O3 and Ca O react C3 A at 1100?; A significant reduction of free calcium oxide in combination with C2 S as C3 S, iron and C3 S can exist simultaneously.(2) Continuous temperature experiments showed the highest reduction rate of iron is 62.9 when particle size of 200 mesh, reducing the ratio of 15%, an basicity of 2.6, the reaction temperature is 1480 ?, reaction time 40 min. Iron can separated by wet magnetic separation, magnetic separation parameters 300 mesh size, the magnetic field strength for the first sweep the election in 3000 Gs, then 1000 Gs selection, iron recovery of 78%.(3) Continuous temperature experiments obtained direct reduced iron, but did not generated C3 S. Analysis of the reasons that Fe2+ replaces part Ca2+ into the C3 S lattice in a reducing atmosphere, Fe2+ is oxidized to Fe3+ when the clinker cooling. Fe3+ can not replace C3 S lattice Ca2+, ions migration leads to C3 S structure is unstable and decompose. Therefore the heating process is divided into two stages.(4) "Two-stage temperature," the first temperature stage is mainly reduce Fe O, the reaction temperature was set at 800?~1000?, holding a certain time so that Fe O fully reduced to iron which avoid the adverse effects to generate C3 S. The second stage temperature set at the generation temperature of C3 S which range 1350? ~ 1500?. Preferred parameters for the experiment was that the first heating up to 1000?, holding time of 40min; the second stage was raised to 1480?, holding time 90min; Cooling rate were rapid can simultaneously obtained Fe and C3 S.Magnetic separation performed after rapid cooling, iron, nickel, copper and so easy to reduce component exists in the form of direct reduction iron alloy furnace as raw material for the remaining components of transforming into a powder with a gelling properties for mining and cement production and filling ingredients, the results of this research can provide a reference for related industries.