Research On Producing Iron From Sulfuric Acid Residue And Making Ferronickel From Laterite Nickel Ore By Coal-based Self-reduction

Sulfuric acid residue is the discharge of slag,which the sulfuric acid plant uses of high pyrite to produce sulfuric acid.At present all over the country were stockpiling a sulfuric acid residue,which will not only take up farmland,but also cause environmental pollution.Iron oxide as the main component of sulfuric acid slag,it is efficient use of sulfuric acid slag has become imminent.As the world's largest nickel production and consumption country,our country need to import large quantities of nickel ore from India,Philippines and other countries,which use to product of stainless steel.The main two methods to product of laterite nickel ore are pyrometallurgy and hydrometallurgy.This papar has been focused on the mineralogucal study of the producing iron from sulfuric acid residue and making ferronickel from low grade laterite nickel ore from Philippines by coal-based self-reduction.This work also conducted study on theory and thermodynamics,optimization of reduction paramenters,and both sulphur and nickel behavior during reduction.The producing iron from sulfuric acid residue by coal-based self-reduction found that: the sulfuric acid residue of S1 study has shown that the reduction product metallization rate increased with increasing the reduction temperature,when the reduction temperature was above 1200?,the reduction product metallization rate as high as 96%.when the C/O ratio and the reduction temperature were added up,the desulfurization rate of 38% to 40%,and the sulfur content of the reduction product was between 1.10% to 1.16%.The sulfuric acid residue of S2 study has shown that when the basicity?w?CaO?/w?SiO₂??of slag of briquettes was 2.5 and the reduction temperature was 1250?,the reduction products of relatively large metallic iron particles,magnetic iron grade of iron powders was 88.58%.the temperature of melting products obtained at 1250? rose to 1500?,the resulting average iron powders of metal iron were at more than 90%.With the basicity?w?CaO?/w?SiO₂??of slag of briquettes was increased,the desulphurization rate of samples improved.When the basicity?w?CaO?/w?SiO₂??of slag of briquettes was 2.5,the desulphurization rate of samples was 87.1%,and the sulfur content of the metal was between 0.15% to 0.16%.the resulting average iron powders of metal iron were at more than 90%,with the increase of the total alkalinity desulfurization rate increases,when the slag phase basicity of 2.5,the desulfurization rate of 87.1%,metallothionein content is reduced to 0.15% to 0.16%.The making ferronickel from low grade laterite nickel oreby coal-based self-reduction found that:?1?Based on the process of coal-based self-reduction and magnetic separation,it was investigated that with increasing grinding time,the yields of Ni increased gradually,which were only added CaF₂.When the grinding time was 10 min,the yields of Ni was 1.32%,which was lower than the theoretical ratio 1.65% of Ni /?Ni + Fe?of the latcritic nickel ore.From the SEM photographs of ferronickel powder could be seen that the metal and slag phase is mutual mosaic,metal particles were very tiny,completely separated metal and slag phase could not be achieved by fine grinding.?2?Based on the process of coal-based self-reduction and melting separation at high temperature,it was investigated that if the C/O mole ratio was not higher than 0.5 and the reduction temperature was kept as 1200? and then increased up to 1500?,the metal could not separate from molten slag for the A series of experiments,which were only added CaF-2.However,when the C/O ratio was added up to 0.6⁰.8,the metal could separate well from the slag and the yields of Fe and Ni increased gradually.But the nickel content in the metal declined from 1.79% to 1.34%.When the C/O ratio increased to 1.2 and the temperature of melting products obtained at 1200? rose to 1550?,the separation of metal from slag could not be realized in B group of tests,which were only added hydrated lime.However,when both of CaF₂ and hydrated lime were added,the metal could separate from slag in C group.In order to increase the content of nickel in the metal,it is necessary to restrain the reduction of iron oxide.When the C/O mole ratio is 0.6,the nickel content of metal could be 1.79%,but the yield of nickle was only 71.3%.