Study On Ni-Fe Enrichment By Coal-Based Direct Reduction-Magnetic Of Poor Laterite Nickel Ore

In recent years,with the development of the world stainless steel industry,the demand for nickel has continuously increased.Nickel sulfide ore has been the main source of nickel for a long time.However,due to the long-term exploitation of nickel sulfide,reserves have dropped sharply.Therefore,great achievements have been made in the research and development of laterite nickel ore in recent years.The lateritic nickel ore is mainly divided into limonite type and silico-nickel-magnesium type.The former is high in iron and low in nickel and should be treated by high-pressure acid leaching and other wet processes.The latter is low in iron and high in nickel,and electric furnace reduction smelting is the mainstream process.There is also a laterite nickel ore that lies between the two types of ore,and the iron and nickel content is very low.For this kind of low-iron laterite nickel ore,no suitable method has been found yet,so it has not been effectively used.For this kind of laterite nickel ore,during the pyrometallurgical treatment,the reduction smelting to produce ferronickel will have a very large power consumption and slag generation when processing lateritic nickel ores with low iron and nickel content;The lower the nickel content,the higher the vulcanizing agent required and the more serious the pollution.In the wet process,the more nickel the reduced roasting-ammonia leaching process consumes more chemical reagents,the more the sulfuric acid pressurizing acid ammonia leaching process is established.Investment,serious equipment corrosion,can not be widely used.In response to these problems,this work conducted a study on "direct reduction-magnetic separation and enrichment of nickel-iron powder" for poor laterite nickel ore(Fel4.88%,Ni1.47%).Through the study,the main conclusions are as follows:(1)Temperature,time,and amount of carbon,Fe2O3?Al2O3 are important factors affecting the reduction process.When the reduction time is the same,The extent of the impact on the reduction effect:Temperature>Fe2O3>Al2O3>Time.As the temperature rises from 1250? to 1350?,the recovery rate has increased separately by 29.02%and 28.75%;The amount of Fe2O3 added is from 0%to 15%,and the recovery rate of nickel is increased by 33.3%,but the recovery rate of iron is decreasing.Before the addition of Al2O3 was 7.5%,the recovery rate and grade of iron-nickel increased.The addition of Al2O3 continued,and the recovery of iron-nickel grade and nickel began to decrease.(2)According to EDS,the spherical nickel-iron particles have a high nickel content,the mass fraction is above 5%,and the iron mass fraction is above 60%.The main phase of the nickel-iron particles is the Fe-Ni phase,and the nickel and iron are basically present in the alloy state.The main component of the aspherical material on the substrate is a silicate containing Si,O,Mg,Al,and a small amount of Fe and C,indicating that the matrix is mainly composed of gangue impurities.(3)The nickel in the concentrate after magnetic separation exists in the form of iron-nickel alloy(Fe,Ni).The main components in the tailings are SiO2,MgO and Al2O3,and the total amount of the three is above 80%.Separation by nitrite and gangue is more obvious.(4)The best reduction parameters for this experiment are:T=1350?,t=30min,C/O=1.8,Al2O3=7.5%,Fe2O3=15%.The grade of iron in concentrate is as high as 83.59%,the grade of nickel is 5.92%,and the recovery rate of nickel is 92.81%.The concentrate can be directly added to the furnace as an alloy raw material for smelting stainless steel.(5)In this experiment,a small amount of Al2O3 and a certain amount of Fe2O3 were added to the material,which greatly improved the reduction effect and the recovery rate of ferronickel.This method provides an effective solution for the treatment of low-grade laterite nickel ore.