Regular Article

Alkaline refining of crude lead: a method of arsenic removal and the behavior of arsenic in the process

¹ State Key Laboratory of Complex Nonferrous Metal Resources Clean Utilization, Kunming University of Science and Technology, Kunming, Yunnan 650093, PR China
² Faculty of Metallurgical and Energy Engineering, Kunming University of Science and Technology, Kunming, Yunnan 650093, PR China
³ School of Metallurgy and Environment, Central South University, Changsha 410083, PR China

^* e-mail: yinsh@kust.edu.cn
^** e-mail: lswei11@163.com

Received: 19 May 2021
Accepted: 12 November 2021

Abstract

In this work, the alkaline refining of arsenic in crude lead was studied with a mixture of sodium hydroxide and sodium carbonate as alkaline refining agents. Taking the arsenic removal rate as the research object, the effects of reaction temperature, holding time, Na₂CO₃:NaOH, the dosage of refining agent were investigated. The arsenic removal rate is 79.09% under the optimum experimental conditions as follows: reaction temperature 823 K, holding time 60 min, Na₂CO₃:NaOH 1:4, refining agent dosage 10%. The oxidation purification mechanism of arsenic was studied by XPS, SEM-EDS, XRD and FT-IR. The results show that arsenic in the crude lead is gradually oxidized by oxygen and lead oxide during arsenic removal process, and the arsenic trioxide is eventually converted into sodium arsenate (Na₃AsO₄) and lead arsenate (Pb₂As₂O₇) in the slag.