Research On Comprehensive Recovery Of Nickel, Iron And Magnesium In Low-grade Silicon-magnesium-type Laterite Nickel Ore

As a strategic metal,nickel has been indispensable in economic development and played an important role in the fields of stainless steel and heat-resistant alloys.At present,the world's proven nickel ore is mainly divided into nickel sulfide ore and laterite nickel ore.In recent years,due to the excessive exploitation of nickel sulfide ore resources,the resources are scarce.At present,the development goal has been transferred to laterite nickel ore.Scholars at home and abroad have done a lot of research on how to enrich ferronickel from low-grade laterite nickel ore.There are still a large amount of high-value magnesium oxide in laterite nickel ore.Therefore,how to realize nickel,iron and magnesium in laterite nickel ore Comprehensive recovery is the key to the development of laterite nickel mines.In this paper,a low-grade silicon-magnesium laterite nickel deposit in a certain area in Yunnan is the research object.The analysis and detection methods such as chemical element analysis,scanning electron microscope(SEM),X-ray diffraction analysis(XRD)are used to determine the mineral composition,mineral element distribution,the phase composition of minerals.The results show that the laterite nickel ore is mainly composed of hydroxyl-containing silicate and oxide minerals,in which iron mainly exists in the form of iron oxides and minerals;nickel and iron have similar chemical properties,and nickel is mainly oxidized Nickel exists;magnesium is mainly found in serpentine in the form of magnesium oxide.According to the characteristics of mineral composition and complex mineral phase of laterite nickel ore,the method of reduction roasting-magnetic separation-hydrochloric acid leaching is adopted to comprehensively recover nickel,iron and magnesium in laterite nickel ore.In the first phase of the experiment,the reduction roasting study of the raw ore showed that when the amount of composite additives is 8%(Na₂CO₃:Ca F₂=1:7),the amount of reducing agent is 8%,the reduction temperature is 1250°C,the reduction time is 60 min,the magnetic separation strength is 150m T,and wet grinding time is 12min,the nickel grade in the ferronickel concentrate is 8.39%and the iron grade is67.70%.XRD analysis of the obtained ferronickel concentrate shows that the main phase is a ferronickel alloy.In the second phase of the experiment,the magnetic separation tailings obtained by the magnetic separation were used as the raw material for hydrochloric acid leaching to extract magnesium.The research results showed that:when the concentration of hydrochloric acid is 3.5 mol/L,the liquid-to-solid ratio is 6:1,the leaching temperature is 60?,the leaching time is 4h and the stirring speed is 300r/min,the leaching rates of magnesium and iron are respectively 98.64%and 67.39%;in order to obtain high-purity magnesium oxide,neutralization hydrolysis is used to remove iron ions in the leaching solution;When the leaching temperature is 60?,when the p H value is adjusted to 6.5,the iron ions in the solution are removed,and the p H value is continuously adjusted to precipitate all the magnesium in the liquid after iron removal;when the temperature is 80?and the p H value is 11.0,the solution The precipitation rate of medium magnesium is 98.86%;Calcined magnesium hydroxide at the calcination temperature of 500?and the calcination time is 360min to obtain the final product of magnesium oxide.The recovery rate of magnesium can be obtained by calculation to be 98.54%.