Study On The Settling Performance And Toxicity Leaching Behaviors Of High-Pressure Acid Leaching Residue Of Laterite Nickel Ore

The settling performance of the high-pressure acid leaching slag of laterite nickel ore in the slag washing process was studied through the experiments of settling performance and toxic leaching behavior to provide a feasible value and are below the threshold determined by the ministry of environment for solid and liquid residues.The effects of different flocculant types,solid content,flocculant dosage and mixing degree on the settling performance of the leaching residue were studied through batch settling experiments.In addition,the settling test results were used to design and calculate the countercurrent decantation washing process,and the effects of p H value,stirring time and temperature on the leaching behavior of the leaching residue were also studied.The main results obtained are as follows:(1)In the washing process of high-pressure acid leaching residue of laterite nickel ore,SC900 is the flocculant with the best performance.The settling speed of the leaching residue is 5.46 mm/min,and the solid content of the obtained supernatant suspension is less than 10%.From 20 g/t to 200g/t solids,the settling speed of the leaching residue does not increase significantly,but as the amount of flocculant increases from 200 g/t to 360g/t solids,the solid content in the underflow decreases significantly;(2)The calculation shows that after 7-Stage washing,the washing efficiency can reach 99.9%.The initial and final concentrations of nickel,cobalt,iron,manganese and chromium are 7.15,0.54,4.01,4.45 and 0.15g/L(initial concentration)and 6.4,0.5,3.6,4 and 0.1 mg/L(final concentration)respectively;(3)The optimized experimental parameters in the alkaline washing process of the high-pressure acid leaching residue are p H 8.5,stirring time2 hours,and temperature 40~oC.Toxicity characteristics the results of leaching experiments showed that the concentrations of elements such as selenium,arsenic,barium,mercury,copper,zinc,lead,cadmium,chromium and nickel were all below the limits of maximum contaminant levels(MCLs).Figure 13,Table 39,References 90...