Thermodynamic and kinetic study of the recovery of tungsten and cobalt from tool waste

Abstract

In the present research work, the recovery of tungsten and cobalt from waste coming from tungsten carbide-cobalt (WC-Co) tools, which are widely used in the metalworking industry, was analyzed. The WC-Co waste was characterized by X-ray diffraction and scanning electron microscopy with microanalysis (SEM/EDS). The process started with the oxidation of the waste to obtain a mixture of oxides (WO 3 and CoWO 4 ). The ΔH and ΔG were calculated both for the oxidation and reduction processes. Thermodynamic and non-isothermal kinetic analyses were carried out to obtain a stability diagram where theoretical and experimental data are defined by transformation lines as a function of temperature; in addition, the apparent activation energy was determined. By a hydrogen reduction process, high-purity tungsten and cobalt in metallic form were obtained. RESUMEN:En el presente proyecto se analiza la recuperación de wolframio y cobalto a partir de residuos de herramientas fabricadas con carburo de wolframio -cobalto (WC-Co), las cuales son muy empleadas en la industria metalmecánica. El residuo de WC-Co se caracterizó por difracción de rayos X y microscopia electrónica de barrido con microanálisis (SEM/EDS). El proceso inició con la oxidación del residuo para obtener una mezcla de óxidos (WO 3 y CoWO 4 ). Se calculó el ΔH y el ΔG tanto para el proceso de oxidación como para el proceso de reducción. Un análisis termodinámico y un análisis cinético no isotérmico entregó una figura donde se combinan datos teóricos y datos experimentales con transformaciones perfectamente delimitadas; además se calculó la energía de activación aparente de este proceso. El proceso de reducción con hidrógeno entregó wolframio y cobalto en forma metálica con alta pureza..

Investigation of the Effect of Tungsten Carbide (WC) Nanopowder on Iron-Based Powder Structural Materials

“…Of particular interest is nanopowder tungsten carbide due to its physicochemical properties: thermal stability, increased elastic modulus, and lower coefficient of thermal expansion compared with carbides of other metals [9,10,11,12]. In [13,14,15] studies on the production of powder steels with alloying nanoparticles of tungsten carbide are presented. Reducing the particle size of tungsten carbide and subsequent products can potentially improve the mechanical properties of the material, such as hardness, viscosity, and transverse tensile strength.…”