In this paper, the leaching behavior of the major metals present in printed circuit boards waste is evaluated, aiming at its recycling by hydrometallurgy. Several leachants were compared (sulfuric, hydrochloric and nitric acids, at 2 M H concentration), at temperatures of 25oC and 90oC and 4 hours of reaction time. Sulfuric acid leaching was not very promising concerning metals dissolution bein...

Titanium dioxide is widely used in the manufacturing of paints, varnishes, lacquer, paper, paperboard, printing inks, rubber, floor covering, and ceramics and so on. White titanium dioxide pigment has been produced by two main processes. The sulfate and the chloride processes. Each of these two routes requires different feedstocks. However, economic and environmental pressures are shifting ...

Bacterial leaching is the extraction of metals from their ores using microorganisms. The most important player in the bioleaching process is. 4 Bacterial Attachment on Mineral Surfaces 200. 5 Microbial Diversity in Bioleaching Environments 200. Minerals are obtained using a leaching process.greater understanding of the mechanism of bacterial leaching of sulphide minerals. This latter process wh...

For the past 60 yr, chromate-copper-arsenate (CCA) has been used to pressure-treat millions of cubic meters of wood in the United States for the construction of many outdoor structures. Leaching of arsenic from these structures is a possible health concern as there exists the potential for soil and groundwater contamination. While previous studies have focused on total arsenic concentrations le...

Bioleaching of spent catalyst using moderate thermophilic chemolithotrophic acidophiles in growth medium without Fe source was investigated with two different pulp densities and three different size fractions. All the experiments were conducted on shake flasks at a temperature of 65 °C. The leaching yield of Ni and Al was found to be promising with very high leaching yield of 92-96% followed by...

In this work, we investigated the role of bacteria from the genera Bacillus and Pseudomonas and fungi from the genera Ž . Aspergillus and Penicillium in the leaching process of two different silicates calamine and garnierite . Since the results obtained with A. niger were better than those with different bacteria, a more detailed investigation of the leaching process with this microorganism was...

In this work, thealkaline roasting and sulfuric acid leaching processes were employed to extract vanadium from the magnetite ore of Saghand mine in central Iran. The response surface methodology based on the central composite design model was applied to optimize the parameters involved in the processes. The studied roasting parameters were temperature (900-1100 °C), sodium carbonate percentage ...

We used a special-purpose glass microfiber sample, Johns-Manville Code 100/475, to study the effects of various acid and alkali treatments on biological activity as assessed by inflammation in the mouse peritoneal cavity, the leaching of Si, and the phase contrast optical microscopy (PCOM) fiber number. We used mild and medium treatments with oxalic acid and Tris buffer and harsh treatment with...

Vegetation at mining sites can produce increased heavy metal leaching by the organic acids and protons originating from root secretion and litter degradation. Batch experiments were conducted to investigate the effects of organic acids and pH on the extraction of Pb, Cd, Zn and Cu from an alkaline mine soil (sampled from a mining site of Chenzhou City, Hunan Province) and an acid mine soil (sam...

In our study we showed the importance of holistic approach to evaluation of chemical stabilization using phosphate amendments, where all aspects of chemical treatments were observed. An extensive evaluation of metal stabilization in contaminated soil and an evaluation of the leaching of phosphorus induced after treatment were performed. The soil from the former zinc smelter area in the Celje re...