Chromium salt is an important industrial material, but vast waste slag containing chrome (Ⅵ) is brought out in the process of its production. The slag is seriously harmful to environments and human health. The technologies on detoxification and comprehensive utilization of chromium containing slag were summarized abroad and at home. And various methods were also described for the detoxification mechanism, technology process, and practical application effects in detail. A new concept for detoxification of chromium-containing slag, furthermore, was put forward by using microorganism.

A novel technology for lead removal with nonliving Rhizopus oligosporus immobilized in calcium alginate was studied. The results show that the main influencing factors include pH value and interfering cations. pH value has different effects on biosorption of various heavy metals and lead adsorption can be proceeded by controlling pH value in a range of 225; interfering cations especially Cu (Ⅱ) can make the adsorption amount of Pb (Ⅱ) decrease by immobilized Rhizopus oligosporus. Desorption efficiency of different eluants and kinetics were investigated. Citrate acid with concentration of 0.3mol•L-1 is the best for the elution of Pb (Ⅱ) and desorption rate is over 98% when the reaction equilibrium reaches 3h. Immobilized biomass keeps high lead biosorption capacity after five cycles of regeneration.

The kinetics qf Thiobacillus ferrooxidans growth was studied using series piezoelectric quartz crystal (SPQC). Cupric ion accelerates the growth of T.ferrooxidans, copper promoting the protein enzyme of T.ferrooxidans, rusticyanin, to form over the range of cupric ion concentration studied. The reaction order of cupric ion in accelerating the bacterial growth is 0.067. The apparent reaction activation energy of the bacterial growth decreases from 25.56kJ/mol to 18.32kJ/mol with the addition of l0mg/lCu (Ⅱ) to the bacterial growth solution of pH 2.0 at initial inoculum of 10 %.

Electrochemical methods were applied to study the anodic behavior of gold and its associated elements, e.g., silver, copper, nickel and iron, in alkaline thiourea solution in the absence and presence of Na2SO3. Gold is difficult to dissolve in alkaline thiourea solution because of the passivation of elemental sulfur produced by the irreversible decomposition of thiourea. However, addition of Na2SO3accelerates the selective dissolution of gold in alkaline thiourea solution. The additive Na2SO3 improves the stability of thiourea in alkaline media, enhances the anodic polarization current of gold greatly, and does not change the passivation states of the associated elements of gold in alkaline thiourea solution. The reaction order of the anodic dissolution of gold in alkaline thiourea solution is 1.65 with respect to Na2SO3, over the Na2SO3concentration range of 0.01 molrl to 0.5 molrl at the potential of 0.34 V vs. NHE. The studies on the kinetics of the dissolution of gold in alkaline thiourea solution show that the Na2SO3 reduces the dissolution potential of gold, and decreases the apparent reaction activation energy of gold dissolution.

A novel method for the production of fine tantalum carbide powder using waste tantalum from the electronic, metallurgical and chemical engineering industries, has been developed at the Central South University of Technology, Changsha, China. Chai Liyuan and Zhong Haiyun describe the technique, which involves a two-stage carburization and stir-ball milling, and examine the effects of various processing factors on the final TaC particle size.