Secondary Lead Alkaline Refining Slag Of Antimony Recovery Process Research

In order to recover valuable metals like Sb, Pb, Sn and prohibit environmental pollution caused by arsenic emission, a new hydrometallurgical process for the treating of lead basic refining slag has been proposed in this dissertation. Based on theoretical analysis, technical studies on arsenic removing and lead leaching were carried out in detail. The results show that effect of basicity and temperature on arsenic removal is remarkable, but that of L/S ratio and time is neglectable. The optimum conditions were determined as follows:temperature 80℃, basicity 70g/L～75g/L, time 1.5h, L/S ratio 4:1. Under above conditions, the average removing ratio of As can reach 93.39%, and the content of As and Pb in leached residue is 0.022% and 2.61%, respectively. During arsenic removal, Sb and Sn in raw material retains in residue with recovery ratio of 98.63% and 93.39%, respectively. For the cyclic experiments of removing As, the cut-off coefficient is set as 50%.Some factors such as HCl addition, NaCl concentration, temperature and reductive reagent have outstanding influences on the leaching ratio of Pb. The average content of Pb and Sn in leached residue is 0.41% and 0.25%, respectively, under the following conditions:NaCl concentration 300g/L, temperature 90℃～95℃, time 2h, HCl 0.6mL/g slag, and Sb2O3 addition is two times of theoretical consumption. During lead leaching process, Sb remains in leached residue with recovery ratio of 98.59%. As a result, antimony concentrate was obtained with grade of 59.25%.Calcium arsenates precipitation method was adopted to remove As from alkaline solution. Due to higher basicity and lower concentration of As, the removing ratio of As is less than 30%～40% at 85℃～95℃with CaO addition of two times of theoretical dosage. Using CaO powder as neutralizer, stannum residue with grade of 26.69% was obtained from mother liquid of PbCl2 crystallization under the following conditions: room temperature, time 1h, pH=4.5～5.0. After stannum precipitation, the pH value was adjusted to 8.5-8.8 and kept constant for 1h to precipitate lead. The content of Pb in obtained residue is 28.79%, and the precipitation ratio of Pb is closer to 100%. In conclusion, the present hydrometallurgical process is simple and flexible. The environmental pollution due to waste emission is prevented effectively. Adopting this process for the treating of lead basic refining slag, the total recovery ratio of Sb can reach 97.24%, and valuable metals like Pb, Sb, and Sn can be recovered in the form of PbCl2, lead residue (Pb 28%-30%), stannum residue (Sn 26%～28%) and antimony concentrate (Sb≥58.87%,Pb≤0.5%,As≤0.03%,Sn≤0.4%), respectively. For It of lead basic refining slag treatment, the consumption of HCl and CaO is 0.684t and 0.262t, respectively, while 0.07t of NaOH and 0.121t of NaCl was simultaneously regenerated. As a result, the production cost is lower, and economic benefit is considerable.