A value-added multistage utilization process for the gradient-recovery tin, iron and preparing composite phase change materials (C-PCMs) from tailings

Zijian Su,Benlai Han,Yuanbo Zhang,Tao Jiang,Yikang Tu,Corby Anderson,Xijun Chen

doi:10.1038/s41598-019-50536-y

Zijian Su, Benlai Han + Show 5 more

Open Access

https://doi.org/10.1038/s41598-019-50536-y

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Abstract

Tin-, iron-bearing tailing is a typically hazardous solid waste in China, which contains plenty of valuable tin, iron elements and is not utilized effectively. In this study, a multistage utilization process was put forward to get the utmost out of the valuable elements (tin and iron) from the tailings, and a gradient-recovery method with three procedures was demonstrated: (1) An activated roasting followed by magnetic separation process was conducted under CO-CO2 atmosphere, tin and iron were efficiently separated during magnetic separation process, and 90.8 wt% iron was enriched in magnetic materials while tin entered into non-magnetic materials; (2) The tin-enriched non-magnetic materials were briquetted with CaCl2 and anthracite and roasted, then tin-rich dusts were collected during the chloridizing roasting process; (3) The roasted briquettes were infiltrated in melting NaNO3 to prepare NaNO3/C-PCMs by a infiltration method. Three kinds of products were obtained from the tailings by the novel process: magnetic concentrates containing 64.53 wt.% TFe, tin-rich dusts containg 52.4 wt.% TSn and NaNO3/C-PCMs for high temperature heat storage. Such a comprehensive and clean utilization method for tin-, iron-bearing tailings produced no secondary hazardous solid wastes, and had great potential for practical application.

Highlights

Tin is a crucial cog in the global economy as its use in electronic solder industry, since the third revolution of science and technology[1,2,3,4]
Magnetite concentrates with very low tin content were produced, and most of tin were enriched in the non-magnetic materials
In this study, Tailing A and Tailing B were mixed first, and the CaO generated from carbonate was enough for the reactions of Eqs (1) and (2), no extra additives were used in this process

Summary

Introduction

Tin is a crucial cog in the global economy as its use in electronic solder industry, since the third revolution of science and technology[1,2,3,4]. Fuming processes were practised to recover tin efficiently from low-grade tin-bearing materials, but the iron oxides were reduced to FeO and generated low-melting-point slags. Those iron oxides were impossible to recover, so the iron-bearing slags became secondary hazardous solid wastes[13,14]. Natural clay minerals (kaolin, diatomite, sepiolite, bentonite, perlite, etc) have porous structure and considerable specific surface area, those minerals were always with excellent adsorbability and suitable for preparing low-temperature C-PCMs (~100 °C)[23,24,25,26] Industrial solid wastes such as fly ash (FA) and blast furnace slags (BFS) were obtained from high-temperature processes, which showed excellent thermostability and corrosion resistibility. Novel routes to utilize FA and BFS for preparing high-temperature C-PCMs (higher than 300 °C) were proposed, and PCMs (NaNO3, Al, Na2SO4, etc) with different operating temperatures were selected[22]

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