Tungsten Industry Research Articles

Evolution and sustainability analysis of global tungsten trade pattern from the perspective of industry chain

Tungsten is an irreplaceable primary material and strategic resource for national economic development and modern national defense security. The endowment of tungsten ore resources in various countries is different; we should not only focus on the availability of tungsten ore itself but also the sustainability of its entire process from upstream supply to downstream industry demand. Analyzing the evolution of the supply and demand patterns of tungsten ore trade from the perspective of the industrial chain, identifying the key supply and demand subjects, and exploring the influencing factors of trade has become an important research topic. Therefore, we construct global tungsten trade networks based on the industrial chain, analyze its overall characteristics, explore critical trade supply and demand entities, and identify China’s trade position. We got some meaningful results: (1) The global tungsten trade networks have prominent power-law distribution characteristics. The trend of trade globalization is evident, but the dominance is still in the hands of a few developed countries or developing countries with developed manufacturing industries. (2) In different parts of the tungsten industry chain, the impact of resource endowment, industrial technology level, and geographical location on the country’s trade role is different. (3) China’s position in the global tungsten resource industry chain and value chain is constantly improving, but there is still a risk of high-end technology being “stuck.” This provides some suggestions for the systematic understanding of the evolution of the trade pattern of the tungsten industry chain and how countries occupy a dominant position in the game of tungsten resources.

Recovery of Low-Concentration Tungsten from Acidic Solution Using D318 Macroporous Resin.

Tungsten is a crucial strategic metal that plays a significant role in various fields, such as the defense industry, fine chemicals, and the preparation of new materials. During the practice of numerous tungsten smelting processes, a large amount of acidic wastewater containing low concentrations of WO3 is generated. The adsorption method, known for its simplicity, effectiveness, and ease of operation, represents the most promising approach for tungsten recovery and is vital for the sustainable development of the tungsten industry. In this study, D318 macroporous resin was used as an adsorbent to investigate its effectiveness in adsorbing WO3 from acidic solutions. Static adsorption experiments revealed that the adsorption capacity of D318 resin for WO3 was 683 mg·g-1. Kinetic analysis indicated that the controlling step for the adsorption of WO3 from acidic solutions by D318 resin was intraparticle diffusion. Thermodynamic analysis demonstrated that the adsorption process was endothermic and could occur spontaneously. By fitting the isothermal adsorption equation, it was found that the Langmuir model was more suitable for describing the adsorption process of WO3 on D318 resin in acidic solutions. The results of dynamic adsorption experiments showed that under optimized conditions, the dynamic adsorption capacity for WO3 was 529 mg·g-1; when using NaOH as the desorbent for cyclic desorption, the desorption rate for WO3 was 98.21%. XPS and SEM-EDS testing and analysis confirmed that D318 macroporous resin exhibited excellent adsorption performance for tungsten in acidic solutions.

A novel strategy for recovery of heavy metals and synthesis of Co-rich alloy from the alkali-treated tungsten residue using photovoltaic silicon kerf waste

The treatment of spent cemented carbides using the conventional alkali-acid leaching process results in the generation of hazardous solid waste tungsten leaching residue. This study proposed an alternative process using the alkali-treated tungsten leaching residue (AW-residue) without the acid leaching step, preserving Co in the residue. By using photovoltaic silicon kerf waste (SKW) as a reducing agent, heavy metals (Co, Ni, W, Nb, and Ta) were efficiently extracted from AW-residue and a Co-rich alloy was obtained. The silicothermic reduction process facilitated the recovery of iron group metals (Co, Ni, and Fe) and effectively captured trace refractory metals (W, Ta, and Nb). Phase separation occurred through reduction reaction and viscosity-driven processes between the Co-rich alloy and the slag. Optimal conditions were identified as 20% SKW addition, MgO crucible, and a holding time of 120 min, achieving a total recovery yield of 95.5%, with specific yields for Co (97.7%), Ni (97.0%), W (82.5%), Nb (76.3%), and Ta (70.5%). A 20 kg pilot-scale experiment confirmed the feasibility of the process, yielding 47.0% Co-rich alloy from AW-residue compared to 48.3% in lab-scale experiment, and producing a harmless slag phase. This environmentally friendly approach promotes sustainable recycling of valuable metals in the tungsten industry.

Mechanisms of demand shortage risk propagation in the multi-layer trade network of global tungsten industry chain

Mechanisms of demand shortage risk propagation in the multi-layer trade network of global tungsten industry chain

Preparation of permeable ceramic bricks with tungsten tailings by two-stage calcination technology

Taking the waste tungsten tailing sand as the main raw material, using its intrinsic mineral composition and particle gradation, ceramic permeable bricks were prepared by adding binder, and the experimental research on the preparation of high-performance ceramic permeable bricks was carried out, and an effective way for the comprehensive utilisation of tungsten tailing sand was also sought.Permeable ceramic bricks were prepared with waste tungsten tailings and ball clay by a two-stage calcination technology, which involves rapid sintering at high temperature (900–1215 °C) and slow crystallisation at low temperature (<900 °C). The pore structure and flexural strength of permeable bricks were improved synthetically. The composition and sintering parameters were optimised, including the ratio of large (>2 mm) to small (1–2 mm) aggregates (1:1 w/w), content of waste ceramic (20 wt%), binder content (10 wt%), sintering temperature (1215 °C), and sintering time (holding time at the maximum sintering temperature; 60 min). The optimised water-permeable ceramic bricks had high permeability (2.53 × 10−2 cm/s) and excellent flexural strength (4.62 MPa). Therefore, through the recovery of tungsten tailing sand and waste ceramics can protect the environment, save resources, and achieve high-value comprehensive utilisation of tungsten tailing sand, with significant economic and environmental benefits, which is conducive to the sustainable development of the tungsten industry.

Evaluation of air quality changes in a Chinese megacity over a 15-year period (2006–2021) using PM2.5 receptor modelling

Air quality impairment has a massive impact on human health, with atmospheric particulate matter (PM) playing a major role. The People's Republic of China experienced a trend of increasing PM2.5 concentrations from 2000 to 2013. However, after the application of the Air Pollution Prevention and Control Action Plan and other related control measures, sharp decreases in air pollutant concentrations were particularly evident in the city of Wuhan (central China). This study analysed major changes in PM2.5 concentrations, composition and source apportionment (using receptor modelling) based on Wuhan's PM2.5 chemical speciation datasets from 2006 to 2007, 2019–2021 and contemporaneous gaseous pollutant values. Average SO2 concentrations decreased by 88%, from the first to the second period, mostly due to measures that reduced coal combustion. However, NO2 only declined by 25%, with policy measures likely being undermined by an increased number of vehicles. PM2.5 concentrations decreased by 65%, with the PM constituents each being affected differently. Coal combustion-related element concentrations, OC, SO42−, NH4+, EC, Cl−, Al, Ca, Cu, Fe, Co and NO3− decreased by 22–90%. Secondary inorganic aerosol (SIA) was initially dominated by (NH4)2SO4 (73%) in 2006, but later dominated by NH4NO3 (52%) in 2021. Receptor modelling identified major sources contributing to PM2.5: Mineral, road and desert dust (MRDD), Secondary sulphate (SECS), Secondary nitrate (SECN), Tungsten industry (W), Toxic Elements of Coal (TEC), Iron and Steel (IRONS), Coal Combustion (CC), Residential Heating (RH), Refinery (REF) and Traffic (TRF). In relative proportions, TEC (−83%), SECS (−64%) and SECN (−48%) reduced their contributions to PM2.5 whilst MRDD increased (+62.5%). Thus, the results indicate not only a drastic abatement of PM pollution in Wuhan but also a change in the sources of pollution, which requires further actions to reduce PM2.5 concentrations to health protective values. Secondary PM and fugitive emissions are key components to abate.

From waste to wealth: Valuable metals recovered from waste tungsten leaching residue by a smelting reduction process using CaO-Fe capture agent

Tungsten leaching residue (W-residue), a hazardous waste generated from the industrial recovery of the spent tungsten carbides, poses a threat to the environment. The W-residue contains high grades of SiO2 and TiO2 oxides, and low grades of high-value metal oxides such as WO3, CoO, Ta2O5, and Nb2O5. Herein, a smelting reduction process was proposed to effectively recover the high-value metals from the W-residue and obtained a medium-entropy carbide (MEC) composite. During the smelting process, the valuable metals were recovered as alloy consisting of (Fe, Co)-rich silicide, (Fe, Cr, W)-rich silicide, and (W, Ta, Nb, Ti)C, respectively. The addition of flux CaO lowered the liquidus temperature of the molten slag, and effective alloy-slag phase separation was achieved by adding Fe as a metal collector to capture the alloy droplets entrapped in the slag. Under the optimal conditions, the total recovery rate reached 86.8%. Moreover, the obtained (W, Ta, Nb, Ti)C as MEC exhibited a Vickers hardness of over 19 GPa and can be used as a wear-resistant alloy. This study proposed a strategy for extracting high-value metals from hazardous tungsten residue, which could complement existing recycling processes towards a closed-loop process in the tungsten industry.

Separation of molybdenum from peroxotungstic acid solution by solvent extraction with TBP and TRPO

An increasing problem facing the tungsten industry is developing an effective separation of molybdenum from peroxotungstic acid solutions due to the similarities of these two metals. This study herein separates molybdenum from peroxotungstic acid solution for the selective production of tungsten from scheelite acid decomposition residue using hydrogen peroxide. Solvent extraction was the main method employed, and the feed was peroxotungstic acid solution containing peroxomolybdic acid. The concentration of tungsten and molybdenum in the feed and the raffinate were measured by Inductively Coupled Plasma (ICP) to characterize the separation efficiency. The results showed that in the peroxide solution, an organic phase of tributyl phosphate (80 %), trialkyl phosphine oxide (2 %), and sulfonated kerosene (18 %) was used effectively to separate molybdenum from tungsten in acid leach solutions. A maximum single-stage separation coefficient of 400 was reached under the following extraction conditions: temperature, 25 °C; contact time 4–6 min; separation time 4 min; and organic to aqueous ratio, 1.2. Using ammonium bicarbonate as the stripping agent, the stripping ratio of molybdenum and tungsten were 83 % and 33 %, respectively, and the corresponding separation coefficient was 10.

Preparation ultrafine WC based on the new tungsten metallurgy system of “no ammonia transformation - no hydrogen reduction”

The preparation of ultra-fine tungsten carbide (WC) is a difficult and hot topic in tungsten industry. The industrial production process requires the need to transform tungsten concentrates to produce ammonium paratungstate (APT) intermediate products followed by hydrogen reduction to produce W, and finally carburization to produce WC. Due to the formation of H2O in the hydrogen reduction process, it is difficult to obtain <100 nm tungsten powder materials. Therefore, in this study, a novel method was introduced that synthesizes ultrafine WC via hydrothermal synthesis of ZnWO4 followed by a carbothermic reduction–carburization process. The findings of this study showed that ZnWO4 with a particle size of 29 nm was synthesized from Na2WO4 solution. This can solve the problem of ammonia‑nitrogen wastewater discharge in the process of APT preparation, and prepare nano-scale raw material. In addition, zinc is volatile at high temperature, which has been widely used in the field of recycling waste cemented carbide. Based on this, the WC mixed powder was obtained by carbothermic reduction of ZnWO4 under the condition of excess C addition, which can inhibit the agglomeration of particles and avoid the production of H2O. Then the single-phase WC with a particle size of 60 nm was obtained by a carburization reaction process at 1300 °C for 3 h. The research intersects tungsten metallurgy with tungsten material preparation, shortens the production process and reduces waste water discharge.

The reliability of the trade dependence network in the tungsten industry chain based on percolation

The unbalanced distribution of globe mineral resources can be addressed partly by the worldwide commerce in those resources. To identify significant international trade linkages and assess the reliability of the global tungsten trade, this paper suggests a modified point mutual information (PMI) and percolation approach. To build a directional network of trade dependence between countries (regions) of representative products at each stage of the tungsten industry chain, we calculate the relationships among trade dependence between countries using countries as nodes, trade dependence intensity as connected edges, and dependence intensity as the ability to cope with risk. The percolation process is replicated using various scenarios (risk disruptions) to filter the network's connected edges. The findings indicate that the downstream and overall networks of the tungsten industry chain are more robust to nonsystemic risks than the upstream and midstream trading networks. Furthermore, the countries with significant total imports and exports are near those with high critical link scores. Additionally, a few countries play an essential role in the tungsten industry chain. The critical countries are upstream tungsten-producing countries, including China, Canada, Russia, and Portugal. At the same time, the United States, Germany, and Japan, which rely on a certain level of in-depth processing technology, are critical downstream countries. Finally, increasing the maximum critical link is crucial for enhancing network reliability. Additionally, it is vital to concentrate on the policy directives of countries with high critical link scores because doing so will help the country create relevant policies and plans.

Research on the Listing Path Selection and Financial Performance of Xiamen Tungsten Industry

Research on the Listing Path Selection and Financial Performance of Xiamen Tungsten Industry

The main transmission paths of price fluctuations for tungsten products along the industry chain

Tungsten is deemed a critical raw material by many nations, given its irreplaceable use in industrial and military applications. In particular, China has high share of global tungsten supply. In this research, we study the tungsten product price fluctuation transmission of trade activities between China domestic market and international trade market from the industry chain perspective. Specifically, we embed the Chinese domestic market into the international trade market to construct price fluctuation transmission network (network-in-network) in tungsten industry chain. Drawing on the analysis ideas of the input-output price impact model, the total transmission impact of the tungsten product price fluctuation is revealed. We then combine the structural path decomposition method and the network cascade theory to identify the main transmission path of tungsten product price fluctuation. The results show that the total transmission impact of price fluctuation between the international trade relationships of cemented carbide in the tungsten industry chain is large. The cumulative transmission of the 3-step price fluctuation transmission paths of tungsten products between the Chinese domestic market and the international trade market accounts for more than 80% of the total transmission. The main transmission path of price fluctuations in the tungsten industry chain exists in the same product. Our research will provide effective information for governments to develop measures to control price fluctuation, thereby minimizing the losses from price fluctuation and transmission.

Explosion characteristics and combustion mechanism of hydrogen/tungsten dust hybrid mixtures

Hybrid mixtures of hydrogen/tungsten dust, which may cause explosions in nuclear fusion reactors and the tungsten industry, have higher risk and more complex mechanism than the explosion of a single combustible medium. The explosion and flame propagation characteristics of hydrogen/tungsten dust hybrid mixtures were studied in a closed combustion tube. The results show that the explosion pressure is dominated by the stoichiometric ratio of the hybrid fuel, while the rate of pressure rise and flame propagation behaviors are mainly dominated by the stoichiometric ratio of the gaseous fuel. The structure and composition of the residues were analyzed. With the change of the hydrogen-tungsten ratio, the composition of the explosion residues can be divided into four regions, corresponding to WO3, WO2.9, WO2.72 and W. Based on the residues analysis, a mechanism for the combustion of a hydrogen/tungsten dust hybrid mixture is further established. The mechanism reveals the combustion mode of tungsten agglomerates in oxygen-rich and hydrogen-rich environments, and explains the effects of heat balance, the mass-consumption rate of oxidizer and the agglomerate radius on the combustion behaviors of the aggregated particles. These results provide a reference for understanding the combustion mechanism of hybrid mixtures containing metal agglomerates and preventing the potential explosion risk.

Facile route for fabricating Co(OH)2@WO3 microspheres from scheelite and its environmental application for high-performance peroxymonosulfate activation

The production integration from mineral resources to materials is favorable for reducing the environmental impacts, shortening the production cycle and improving resource utilization. In this work, we developed a facile and eco-friendly method to prepare Co-doped WO3 microspheres from low-grade scheelite, by which the use of chemicals and discharge of wastewater were significantly decreased compared with traditional preparation methods. The as-prepared Co(OH)2@WO3 composite was employed as a peroxymonosulfate (PMS) activator for rhodamine B (RhB) degradation. Density functional theory (DFT) calculation illustrated its adsorption capacity for PMS, and the adsorption effect of Co(OH)2 was more obvious than WO3. Compared with the Co(OH)2, the composites displayed excellent catalytic performance, by which RhB was completely removed within 7 min and a high rate constant of 0.57 min−1 was achieved. This was attributed the lower electrical transfer resistance and better electrical conductivity of the composites confirmed by different electrochemical tests. Quenching experiments revealed that both SO4•− radicals and 1O2 were involved in the reaction system, and 1O2 served as the dominant reactive oxygen species. Furthermore, catalyst stability was assessed by reuse experiments and no significant decrease of degradation efficiency was noticed after five cycles, suggesting good stability of the catalyst. This work might shed new light on preparing efficient catalyst from natural minerals, and the findings would be helpful for the development of the tungsten industry and the improvement of organic wastewater treatment.

A new process for the efficient decomposition of low-grade scheelite based on the formation of insoluble calcium fluorophosphate

With the exhaustion of wolframite and scheelite concentrates, low-grade scheelite has gradually become the main raw material of the tungsten industry. The current processes used for leaching low-grade scheelite with sodium hydroxide or sodium carbonate in an autoclave have the disadvantages of low tungsten leaching efficiency and the requirement of a large leaching reagent dosage. In this study, a new process for leaching low-grade scheelite by using a mixture of sodium phosphate, sodium hydroxide and calcium fluoride is proposed. In the leaching process, scheelite is converted into calcium fluorophosphate while transferring WO42− from the mineral to the solution. To explore the conditions favourable for the formation of calcium fluorophosphate during leaching, thermodynamic analysis of the Ca-W-P-F-H2O system was carried out. The results show that calcium fluorophosphate can be formed over a wide range of pH values. Increasing the concentration of total phosphorus and total fluorine in the solution is beneficial to the decomposition of scheelite. The effects of various parameters on the leaching of low-grade scheelite were studied, and the optimum process parameters were determined. A total of 98.21% of the tungsten can be leached from low-grade scheelite using 2 times the theoretical amount of sodium phosphate, 1.5 times the theoretical amount of calcium fluoride, a sodium hydroxide to ore mass ratio of 14%, and an L/S ratio of 4:1 at 453 K for 3 h, with a residual phosphorus concentration of only 0.12 g/L in the leaching solution. Mineralogical analysis of the leaching residue shows that most of the associated mineral calcite in the low-grade scheelite is not decomposed, which indicates that selective and efficient decomposition of scheelite is achieved by using this novel process.

Problems of the mineral resource base that stand before the tungsten industry of the Russian Far East

Problems of the mineral resource base that stand before the tungsten industry of the Russian Far East

The evolution and influencing factors of international tungsten competition from the industrial chain perspective

The concentrated supply of tungsten and its important role in strategic emerging industries have led to intense competition between importers. Based on trade data from 2000 to 2018, this study analyses the evolution and influencing factors of international tungsten competition from the industrial chain perspective using a complex network method and an extended gravity model. First, the results reveal that competition varies at different stages. Upstream competition is unstable; the import market for upstream and midstream products is expanding; downstream competition is becoming increasingly intense, and importers are gradually becoming integrated. Second, global tungsten competition is getting tighter, with the fiercest competition between Asia and Europe. In addition, the US, Japan and Germany has remarkable competitiveness in mid-downstream stages of the industrial chain. Finally, an analysis of the influencing factors shows that consumption level drives the competition for upstream and midstream products, while technological progress and Sino-US trade frictions impede the competition of mid-downstream products. Besides, rising political risk in exporting countries intensifies competition throughout the tungsten industry. Corresponding policy recommendations are proposed to promote a stable and orderly trade competition environment in the tungsten industry.

Toward Greener Synthesis of WC Powders for Cemented Tungsten Carbides Manufacturing

Tungsten carbide (WC) is the most important tungsten compound, and the main component of WC-Co cermet composites. WC-Co are widely used engineering materials due to the combination of high hardness and strength of tungsten carbide with the toughness and plasticity of the metallic binder. The direct synthesis of WC from tungsten concentrate containing ∼70% WO3 has been achieved by carbothermic reduction. Mineral/carbon black mixtures were prepared by planetary ball milling and subjected to annealing at 1150 °C in flowing Ar. Specific leaching treatments have been developed to remove foreign phases and obtain pure WC powders. This new process allows about 50% energy saving, −34% CO2 emissions, and significantly lower amounts of industrial waste, with respect to the classical hydrometallurgical tungsten extraction and subsequent pyrometallurgical WC synthesis, widely used in tungsten industry. WC powders obtained by carbothermic reduction of the mineral were employed to prepare sintered WC-8 wt %Co samples that showed high density (>99%), hardness (1490 HV), and toughness (14.6 MPa·m1/2). These findings demonstrate, for the first time, that the carbothermic reduction of tungsten concentrates does represent a viable process for energy efficient and sustainable synthesis of WC powders to be used in the production of cemented carbides.

Harmless Treatment and Valuable Metals Recovery of Tungsten Leaching Residues: A Thermodynamic and Experimental Study

Tungsten leaching residues are industrial wastes that are largely generated during commercial tungsten production. The residues have been classified as hazardous solid wastes due to the presence of toxic elements. On the other hand, the residues contain valuable elements, such as W, Mn, and Fe which can be recovered for economic benefit. To utilize the residue, a carbothermic reduction process was studied to achieve the effective utilization of the residue and sustainable development of the tungsten industry. Fe-W-Mn alloys and nontoxic slags were obtained successfully at 1450°C, and can be used to produce wear-resisting iron materials and glass–ceramics, respectively. The more effective metal–slag separation was achieved by controlling the MnO concentration of the slag, which impacted the liquidus temperature and the viscosity of the slag. This study confirmed a method for utilizing the tungsten residues, which could be a step toward practical industrial-scale techniques.

Recovery of valuable metals from molybdenum-removal sludge by reverse sulfurization leaching

Selective precipitation is the main process used to remove molybdenum from tungstate solutions by the tungsten industry in China. The process exploits the fact that molybdenum is a sulfophile whereas tungsten is an oxyphile. First, the sulfur ions replace oxygen and convert the molybdate to thiomolybdate, then a moderate amount of additives (copper compounds) are reacted with the thiomolybdate to form complex precipitates. We call the filtered wet precipitate “molybdenum-removal sludge”. The main components of the sludge are molybdenum, copper and sulfur, infiltrated by some amount of tungsten due tomechanical entrainment. Based on the fact that copper is a typical sulfophile, it is possible that copper ions can react withthe sulfur of the thiomolybdate, thus converting it to soluble molybdate. This is actually the reverse of molybdenum sulfuration process, so we therefore call it the “reverse sulfuration process.” Based on the leaching thermodynamics and structure characteristics of this kind of sludge, a new treatment process was developed in this work. About 90% of tungsten and 15% of molybdenum were washed out with ammonia water when the pH > 9. The recovery rate of molybdenum was close to 70% when a stoichiometric amount of copper ions (with sodium hydroxide 4 mol/L) were utilized for the reverse sulfurization leaching. The leaching rate of molybdenum obtained on leaching with 2 mol/L sodium hydroxide for 120 min at 80 °C and then fixing with copper chloride was 94.4%, and 87.67% of sulfur ions were fixed in the form of an amorphous CuS compound.