Reclamation of tungsten from carbide scraps and spent materials

Srivastava, Rajiv Ranjan; Lee, Jae-chun; Bae, Mooki; Kumar, Vinay

doi:10.1007/s10853-018-2876-1

Cited by 32 publications

(25 citation statements)

References 58 publications

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“…Other methods, such as direct hydrometallurgical processing have also been proposed. Grinding or sludge wastes can be treated using acidic leaching without oxidative pretreatment because of the faster dissolution kinetics and better exposure of the binder; however, it is unfeasible for most hardmetal scrap . Another studied possibility is electrolysis, where oxidation of the carbide occurs at the anode, which either leaves the WC skeleton intact or produces an insoluble tungsten compound such as tungstic acid .…”

Section: Introductionmentioning

confidence: 99%

Comparative Life Cycle Assessment of Hardmetal Chemical Recycling Routes

Aromaa

Rinne

Lundström

2022

ACS Sustainable Chem. Eng.

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Secondary hardmetal is a large part of the supply for new hardmetal products, yet the environmental impacts of hardmetal recycling remain unknown to a large degree. The goal of this study was to evaluate the gate-to-gate impacts of tungsten and cobalt recovery by chemical recycling. The LCI data was obtained from process simulations and the environmental impact categories were calculated using GaBi software. The simulations were used to study process performance and to investigate the effect of process parameter variation on the environmental impact indicators. Compared to primary production, chemical recycling decreased impacts by more than 50% in all investigated impact categories. The global warming potential for treating 1 metric ton of hardmetal scrap by standard chemical recycling to APT and Co(OH) 2 was 6121 kg CO 2 -eq., freshwater consumption 142 m 3 , eutrophication potential 2.3 kg P-eq., ozone depletion potential 0.0030 kg CFC-11-eq., acidification potential 91 kg SO 2 -eq., and photochemical ozone formation potential 11 kg NO x -eq. Process hotspots depended on the impact category of interest, but in most cases included oxidation of the scrap material and APT production. Major contributors to environmental impacts included electricity consumption, leaching chemicals, and heating required by the oxidation.

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Section: Introductionmentioning

confidence: 99%

Comparative Life Cycle Assessment of Hardmetal Chemical Recycling Routes

Aromaa

Rinne

Lundström

2022

ACS Sustainable Chem. Eng.

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“…Direct methods present many advantages (high recovery rates, good quality of the powders, good grain materials) but some drawbacks (difficult separation of the binder and need for costly materials and equipment). The zinc method [32][33][34][35] and the Coldstream process [23,36] are the two main direct methods. In the zinc method, molten zinc (900-1050 °C) infiltrates the WC-Co scraps, reacts with the binder, and forms intermetallic compounds (especially a zinc-cobalt alloy).…”

Section: Introductionmentioning

confidence: 99%

Study of the Processing of a Recycled WC–Co Powder: Can It Compete with Conventional WC–Co Powders?

Mégret

Vitry

Delaunois

2021

J. Sustain. Metall.

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Cemented carbide tools suffer from many issues due to the use of tungsten and cobalt as raw materials. Indeed, those are listed by the European Commission as “critical raw materials” since 2011 and by the US Department of Interior as “critical minerals” in 2018. To remain competitive with the conventional high-speed steels, less performant but cheaper, WC–Co tools can be recycled. In the present paper, a WC–7.5Co powder, recycled by the “Coldstream” process, has been sintered with vacuum sintering. As preliminary experiments have shown that the sinterability of the powder is low, the sintering temperature was set at 1500 °C to achieve full density. In parallel, the influence of ball milling conditions (rotation speed and milling medium) on the reactivity of the recycled powder has been studied in terms of grain size distribution, hardness, and fracture toughness. The optimized milling conditions were found to be 6 h wet milling, leading to a hardness of about 1870 HV30 and a toughness of about 10.5 MPa√m after densification. The recycled powder can thus totally compete with conventional powders, opening avenues for the recycling of cemented carbide tools. Graphical Abstract

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“…Therefore, it is highly essential to improve recycling efficiency of Co in multiple resources, and recycle the waste materials and Co compounds generated during the production of Co products. Domestic tungsten resources are mainly wolframite (Fe, Mn) WO 4 and scheelite CaWO 4 7 . Therefore, the recovery of tungsten resources to develop secondary tungsten resources is of great significance to implement circular economy policies and for the shortage of tungsten resources because of the continuous development of tungsten resources.…”

Section: Introductionmentioning

confidence: 99%

“…Domestic tungsten resources are mainly wolframite (Fe, Mn) WO 4 and scheelite CaWO 4 . 7 Therefore, the recovery of tungsten resources to develop secondary tungsten resources is of great significance to implement circular economy policies and for the shortage of tungsten resources because of the continuous development of tungsten resources. Secondary resource treatments for tungsten include: WC hard waste (cutting insert, hard metal button, cutting tool tip, and wear-resistant roller) and WC soft waste (lathe cuttings, wastes, processing wet sludge, and dry sludge).…”

Section: Introductionmentioning

confidence: 99%

Effect of Fe content on the mechanical properties of a regenerated cemented carbide

Wang

Zhang³

et al. 2021

Int J Applied Ceramic Tech

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Impurity elements such as Fe, Ni, Zn, and Ca introduced in the recycling process of regenerated cemented carbide affect the structure and mechanical properties of the regenerated cemented carbide. Unlike other impurity elements, Fe and Co belong to group VIII elements and have similar chemical and physical properties. The nature of Fe is closely related to the size and type of waste cemented carbide during recycling and pollution observed during production. Waste cemented carbide is processed via zinc melting to obtain WC, and the regenerated YG10 cemented carbide was prepared via low‐pressure sintering in this study. The effects of impurity element Fe on the microstructure and mechanical properties of a regenerated cemented carbide were studied via X‐ray diffraction, scanning electron microscopy, magnetic property tests, and mechanical property tests. This study demonstrates that an increase in the Fe content leads to a decrease in the bending strength and hardness; further, the mechanism of grain growth caused by the increase in Fe content is revealed. In addition, the mechanism of decreasing wear resistance of the regenerated YG10 cemented carbide with increasing Fe content was discussed. The introduction of Fe as an impurity has evident adverse effects on the mechanical properties of the alloy. To satisfy the production requirements, the Fe content in the mixed powder must to be retained within 0.5%.

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Reclamation of tungsten from carbide scraps and spent materials

Cited by 32 publications

References 58 publications

Comparative Life Cycle Assessment of Hardmetal Chemical Recycling Routes

Comparative Life Cycle Assessment of Hardmetal Chemical Recycling Routes

Study of the Processing of a Recycled WC–Co Powder: Can It Compete with Conventional WC–Co Powders?

Effect of Fe content on the mechanical properties of a regenerated cemented carbide

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