Treatment and Recovery of Nickel Rich Precipitate From Plating Plant Waste/Nikeliavimo Gamyklų Atliekų Apdorojimas Ir Nikelio Išgryninimas/Переработка Отходов И Получение Чистого Никеля На Заводах По Обработке Никеля

Abstract

Abstract. Nowadays, with the environmental regulations becoming more and more stringent and growing pressure on the conservation of mineral resources, recycling has been gaining interest to develop economically-viable refining technology. As the costs of the wastewater disposal increase (especially in the metal finishing industry) more emphasis is being placed on the recovery and recycling of valuable chemicals contained within these streams. In this study, a commercial plating plant filter waste (PPFW) was examined as an alternative source for the recovery of Ni as a nickel rich precipitate. The treatment tests performed by H 2 SO 4 leaching method showed that dissolution amounts of metals such as Ni, Cu, Zn and Cr were affected by leaching time, temperature and acid concentration. Although the dissolution of metallic compounds almost was completed within the one hour of the extraction time, a rapid and higher dissolution amounts of Ni within the first minute of the leaching process (approximately 81% of the total extractable amount of Ni is extracted at the beginning period for 24 °C) indicated that the usage of this waste as a source of Ni has an advantage compared to Ni recovery from natural ores. A kinetic study carried out to clarify the dissolution of Ni, showed that a series of rate controlling steps, both chemical and diffusion reactions, was involved in the observed kinetic. After leaching, the filtered solution was subjected to two stages of controlled precipitation carried out at a pH of about 4-5.5 and about 8 to produce the solids containing non-nickel and nickel respectively. The precipitation test performed by NaOH or MgO showed that almost all of the dissolved Ni ions were seperated from the solution. Based on the XRD and IR analysis, it was found out that a final precipitate, obtained by the use of NaOH, could be characterized as a disordered α-Ni(OH) or as a blend of α and β-Ni(OH) 2 , as for the MgO, the precipitate composed of mainly β-(Ni(OH) 2 ) phase and/or α-(Ni(OH) 2 ) phases.

Nickel speciation in cement-stabilized/solidified metal treatment filtercakes

“…Kurama [34] has also reported -nickel hydroxide in plating sludge, although his XRD pattern shows surprisingly high intensities for this relatively disordered phase, unlike our data. The -nickel hydroxide in the filtercake may have a turbostratic nature that explains the low XRD intensities.…”

Development of ferritization processing of galvanic waste involving the energy­saving electromagnetic pulse activation of the process

“…Known methods of galvanic production wastewater treatment come down to its processing into low-soluble hydroxides with their separation in the form of galvanic sludge [1]. The ions of heavy metals easily leach from these unstable substances into the soil and water objects, thereby causing irreparable damage to the entire ecosystem [2]. Ukraine annually accumulates in specially designated places about 2.26 million tons of toxic wastes from acids, alkalis, and salts, and 0.98 million tons of galvanic sludge, which is considerably greater than in other European countries [3].…”

Archives of Environmental Protection

“…The surface treatment of chromium-nickel steel through pickling and electropolishing processes generates the post-galvanic sewage containing high concentrations of nickel, chromium, iron, and copper. The treatment of this kind of effluent is usually performed by adjusting pH from 8 to 11 so as to precipitate the metallic cations as the corresponding hydroxide which, as a sludge, is then separated during filtration (Kurama 2009). In the case of a mixture of metals, their hydroxides do not precipitate completely at a single pH and each metal hydroxide has its own favorable to precipitate a range of pH (for nickel 10.0-10.5 pH, for copper 8.5-9.5 pH), beyond which it tends to resolubilize.…”