Flotation Performance, Structure-Activity Relationship and Adsorption Mechanism of O-Isopropyl-N-Ethyl Thionocarbamate Collector for Elemental Sulfur in a High-Sulfur Residue

Zhonglin Dong,Tao Jiang,Fan Zhang,Bangsheng Zhang,Guiqing Liu,Bin Xu,Fang Wang

doi:10.3390/met11050727

Zhonglin Dong, Tao Jiang + Show 5 more

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https://doi.org/10.3390/met11050727

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Journal: Metals	Publication Date: Apr 28, 2021
Citations: 3	License type: CC BY 4.0

Affiliation: Central South University, Northeastern University

Abstract

O-isopropyl-N-ethyl thionocarbamate (IPETC) collector was used to selectively recover elemental sulfur from a high-sulfur residue, and its flotation performance, structure–property relationship and adsorption mechanism to elemental sulfur were studied. The raw ore flotation test showed that IPETC displayed superior flotation performance to the elemental sulfur compared with sodium ethyl xanthate (SEX) and ammonium dibutyl dithiophosphate (ADDTP) collectors. Pure mineral flotation and adsorption experiments further demonstrated that among the three collectors, IPETC had the strongest collecting power and the optimum selectivity towards elemental sulfur. The structure–property relationship research based on density functional theory (DFT) calculation supported the above conclusion. The adsorption mechanism analysis manifested that IPETC adsorption on elemental sulfur surface was a chemical process by separately generating normal covalent bond between carbonyl S atom and S atom and a backdonation covalent bond between O atom and S atom, which was confirmed by the FTIR spectrum analysis result. IPETC exhibits excellent collecting ability and selectivity for elemental sulfur and therefore it has bright application prospects.

Highlights

Elemental sulfur is an important chemical material and has been widely used for producing sulfuric acid and other products such as fertilizers, matches, food preservation agents, carbon disulfide, cement, gun powder, surfactants, detergents, pharmaceuticals, pesticides and vulcanized rubbers [1,2,3,4,5,6,7]
Pure mineral flotation and adsorption experiments further proved that the collecting power and selectivity of Isopropyl-N-Ethyl thionocarbamate (IPETC) to elemental sulfur are the optimum among the three collectors
The bond length of C=S/P=S covalent bond, Mulliken population and frontier orbital energy difference between collectors and minerals manifested that the selectivity of three collectors to elemental sulfur is in the order of IPETC > ammonium dibutyl dithiophosphate (ADDTP) > sodium ethyl xanthate (SEX)

Summary

Introduction

Elemental sulfur is an important chemical material and has been widely used for producing sulfuric acid and other products such as fertilizers, matches, food preservation agents, carbon disulfide, cement, gun powder, surfactants, detergents, pharmaceuticals, pesticides and vulcanized rubbers [1,2,3,4,5,6,7]. Elemental sulfur is usually the by-product of hydrometallurgical leaching of nonferrous sulfide ores. Oxygen pressure acid leaching of zinc concentrate (sphalerite) can yield large amounts of elemental sulfur [8,9,10,11,12,13,14], and the overall reaction is shown in Equation (1). Zinc in sphalerite is transformed into zinc sulfate which can be used to produce zinc metal through electrowinning and sulfur remains in the residue in the form of elemental sulfur [15,16,17,18]. The residue is considered to be acid-producing since its sulfur component can react with oxygen and water to generate thiosalts and sulfuric acid [19]

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