AQUEOUS AND LOW TEMPERATURE PROCESSING OF MINERALS, METALS AND MATERIALS

This study focuses on hydrometallurgical treatment of lateritic nickel ores obtained from Manisa - Caldag region of Turkey. 1.58 % of nickel and 0.12 % of Co containing lateritic ores characterized by both chemical analysis and x-ray diffraction. Leaching conditions of ore were carried out by determining the optimum parameters such as sulphuric acid concentration, leaching duration, stirring rate and solid / liquid ratio. Nickel and cobalt were extracted in the form of nickel sulphate and cobalt sulphate solutions after the leaching, respectively. The dissolution of iron in the ore during the leaching process was monitored. Finally several hydrometallurgical purification techniques were carried out to obtain relatively pure nickel and cobalt solution for further reduction / refining techniques.

Self-propagating high temperature synthesis processes are one of the highly productive and economically reasonable methods for the metallurgy industry. The latest stage in the production of advance ceramic powders by SHS method was the leaching process, in which the elimination of several impurities such as MgO and magnesium borates from SHS product was took place by using concentrated hydrochloric acid solutions. Leaching of SHS product resulted in the production of high purity advance ceramic powders together with Mg and B containing spent solution. In this study, removal of zirconium, magnesium and boron compounds from relevant chloride containing spent solutions was aimed. The effects of chemical reagents, pH of the solution on the precipitation efficiency were investigated in the study. Chemical analysis and the characterization of solid phases by using x-ray diffraction and chemical analysis were the latest stage.

Flotation assisted with acidic non-oxidative leaching of the carbonate feed has been presented. The untreated feed is hardly-upgradeable by standard procedures due to a very fine mineralization and severe problems in liberation of copper-bearing sulphides. The acidic leaching results in chemical effective liberation of copper and valuable met-als sulphide particles finely disseminated in a carbonate gangue. For this leaching a part of the clay-carbonate feed material was separated from the commercial flotation circuit and subjected to leaching with sulfuric acid prior to further flotation. The feed suspension, after non-oxidative leaching, was returned to the flotation circuit in order to separate freshly precipitated gypsum and was finally subjected to cleaning flotation. The combined leaching-flotation process was eventually successfully applied on the in-dustrial scale. In this paper a flotation circuit with acidic leaching of the feed was pre-sented. Flotation indices of the chemically modified feed were compared with the stan-dard system without chemical pretreatment. After several months of operation of the new technological system, a significant increase of copper and other metals recovery was observed along with an increase in concentrate grade. On the basis of technologi-cal experience and additional laboratory investigations application and development of proposed chemical pretreatment and further full hydrometallurgical processing of flota-tion concentrates for improving metals recovery is considered

Different cyanide forms exist according to their composition and stability, each one with different toxicity grade. The most toxicity is the free cyanide. The mensuration of concentration of the cyanide can be carried out by diferents methods.The free cyanide in solution can transform to less toxic forms by means of the natural degradation, precipitation, cyanide recovery, adsorption has more than enough activated carbon and oxidation being this last one the most applied. This paper presents the evaluation of degradation tests for oxidation of cyanide applied to solids and liquids effluents, and pulps of different treatments in the mill, located in the county of Segovia at Antioquia and Marmato, at Caldas - Colombia.The technological alternatives researched for at the oxidation of cyanide in effluents of solids and liquids taken in Segovia, were: Sodium hypochlorite, hydrogen peroxide and the combination of the reagents before mentioned.For the treatment with sodium hypochlorite it is required 12.5 kg NaOCl/kg CN- - for a time of 40 minutes; While for the process with hydrogen peroxide it is needed 3.5 kg H2O2/kg CN- - for a time of 2.5 h. For the combination of the methods of the sodium hypochlorite with hydrogen peroxide is required 2.5 kg H2O2/kg CN, with 5 kg NaOCl/kg CN- for a time of 20 minutes. The samples taken in Marmato, correspond to pulp mineral that leave the extractive process and that it contains high cyanide concentrations. In these samples the degradation was applied by oxidation using hydrogen peroxide and the Caro´s acid (AC).The speeds in the degradation indicated a reduction of the cyanide content in more than 93% in a time of 4 h for the use of the hydrogen peroxide and, 5 minutes for the use of the Caro´s acid, with relationships among the H2O2/CN- of 2,5 and AC/CN- of 2 and H2SO4/H2O2 of 2.

HfO2 is expected to be an alternative gate dielectrics used in ultra large scale integration (ULSI) to the conventional SiO2 thin film. It is required that the materials used in ULSI are sufficiently purified to avoid unexpected errors. Commercial Hf, however, contains > 20,000 mass ppm Zr, which is the most difficult impurity to be removed and causing flat-band voltage shift. Therefore, it is important to establish process of removing Zr from Hf. Furthermore, high purity Hf is indispensable for investigating the intrinsic properties of Hf metal.A lot of processes have been proposed for separation of Hf and Zr. In the industry, solvent extraction and chloride distillation are used. In addition, solid/liquid extraction methods such as chelating or solvent impregnated resins have been reported. Among those we focus on anion-exchange separation which is very useful to purify some transition metals. Anion-exchange behavior of Hf(IV) and Zr(IV) has been reported by a several researchers, but the reported distribution coefficients of Hf(IV) and Zr(IV) vary widely. In this work, we investigate the anion-exchange behavior of Hf(IV) and Zr(IV) by the batch experiment in the condition identical to that in the column separation as possible and determine the optimum condition for separating Zr from Hf.Strongly basic anion-exchange resin, DIAION SA10A supplied by Mitsubishi Chemical Corp., was used. The examined species were dissolved into HCl solutions in the form of chlorides. The mixture of anion-exchange resin and the solution containing the examined species was shaken in the thermostat bath for a certain time. After the resin was filtered, the concentration of the species in the initial and final solution were analyzed by inductively coupled plasma atomic emission spectroscopy, ICP-AES.As a result, adsorption isotherms of Hf(IV) and Zr(IV) from HCl solutions follow the Langmuir isotherm and the distribution coefficient of Zr(IV) is higher than that of Hf(IV) in whole examined range, 8 – 11 M HCl and at 10 – 40 °C. In the range of < 8 M HCl both Hf(IV) and Zr(IV) are not adsorbed on anion-exchange resin. It indicates that negatively charged species does not form in this hydrochloric acid concentration range. And adsorption of both Hf(IV) and Zr(IV) are not as strong as reported. The separation factor assessed from the distribution coefficients determines that the optimum separation condition is in 9.5 M HCl and at 20 °C.