Study On Low Grade Nickel Matte Sulfuric Acid Roasting-Water Leaching Process

Nickel is an important non-ferrous metal and is used in various fields of life because of its excellent physical and chemical properties.At present,the growth rate of nickel in China is far less than the growth of demand,and the relationship between supply and demand is not balanced.As China's high-grade nickel ore is exhausted,nickel ore,which is of low grade and difficult to mine,becomes the main raw material for nickel products.The existing process processes these ores,which have the problems of high cost,large metal loss,and poor economic efficiency.It is of great significance to the development of the nickel industry to use low grade nickel matte as raw material,improve the process,and carry out simultaneous extraction of Ni,Cu and Co.In this paper,low grade nickel matte was treated by sulfuric acid roasting-water immersion method.The effects of various factors on the extraction rate of each metal during roasting and water immersion were studied respectively.The optimum process parameters were determined.The two-stage roasting iron removal experiment was used to remove some impurity ions.This process enables efficient use of resources.The main conclusions are as follows:1.The reaction of metal sulfides reacting with oxygen to form metal oxides during the calcination of sulfuric acid,the reaction of metal sulfides with oxygen to form metal sulfates,the reaction of metal sulfides with sulfuric acid and oxygen to form sulfates and sulfur dioxide and water.The reaction,the reaction between the metal oxide and sulfuric acid to form sulfate and water were respectively subjected to thermodynamic analysis.The results showed that the reaction spontaneously proceeded under the experimental conditions around 200?.2.The effects of various factors on the metal conversion rate in the process of low grade nickel matte sulfuric acid roasting were carried out by single factor experiment and orthogonal experiment.The calcination temperature,calcination time,acid ratio,low grade nickel matte raw material particle size,roasting process and oxygen rate were obtained.The optimum calcination conditions were determined as follows:calcination temperature 200?,calcination time 2.5h,raw material particle size 160-180,acid ratio 3.5:1(g/g),and oxygen permeation rate 20mL/min.The order of influence of various factors on the extraction rate of Ni is:acid ratio>time>particle size>temperature>oxygen rate.Under this optimal condition,99.23%Ni,96.46%Cu,91.72%Co,and 85.48%Fe can be extracted.3.The single factor experiment was carried out on various influencing factors in the process of water immersion.The effects of water immersion time,water immersion temperature,water immersion liquid-solid ratio and stirring rate on metal leaching rate were obtained.All four factors can improve leaching rate.The optimum reaction conditions are water immersion temperature 80?,water leaching time 60 min,liquid-solid ratio5:1,stirring rate 300r·min-1.4.Two-stage roasting and iron removal studies were carried out on the basis of the first-stage roasting.The effects of two-stage roasting time and temperature on iron removal were studied.The results showed that the two factors have an effect on iron removal.When the temperature is 600? and the calcination time is 5h,the leaching rate of Ni,Cu and Co is basically not in the case of change,the leaching rate of Fe can be reduced to about 55%.