The Recycling Of The Biological Leaching Technology Of Stainless Steel Pickling Waste Residue

In stainless steel production process, due to the high temperature oxidation process can make the surface into a layer of film of oxide skin, easily to be removed from the surface of stainless steel deep processing first, and the traditional treatment process is the acid pickling process, thus will produce large amounts of acid pickling wastewater, acid wastewater in mainly contains the metal ions such as Ni, Cr and Fe, in order to make the wastewater discharging standard, most of the stainless steel mills will be adding the lime,sodium hydroxide and other drugs such as Ni, Cr and Fe fractional precipitation to remove metal ions, and then to pressure filtration dehydration of sediment, transfer the metal ions from the water to solid, the forming of stainless steel pickling waste residue. Numerous large and small stainless steel manufacturer in China, every year the pickling waste residue is piling up, these belong to hazardous waste slag, is recognized at home and abroad.Traditional treatment technology is more extensive, mainly using industrial sulfuric acid or spent acid soaking for stainless steel pickling waste will be one of the state from solid to heavy metal ions, and then recycling, but as to improve the production process of stainless steel, value high metal content in slag is more and more low, then use the traditional industrial sulfuric acid soaking, cost is very high, almost no earnings, not only high requirements for equipment, and industrial sulfuric acid in the process of transportation and use are easy to produce risk.Biological leaching technology for low quantity of acid consumption, low processing cost, high leaching rate, safe and environmental protection has caused wide public concern.There is no use of the recycling of the biological leaching technology of slag of stainless steel articles. Using autotrophic bacteria, for the first time in this article for cheap pyrite sulfur powder and energy substrate experiment, by changing the experiment conditions and to explore the recycling stainless steel pickling waste residue of Ni, Cr, Fe and so on conditions on the optimization of metal ions, Under the condition of optimization, to explain and analyze its mechanism of leaching residue after potential toxicity, lay a foundation for the practical application of biological leaching technology. For stainless steel waste harmless and resource is of great significance.Studies have shown that using Acidithiobacillus thiooxidans(At), Acidithiobacillus ferrooxidans(Af) and Leptospirillum ferriphilum(Lf) three kinds of bacteria and auxiliary matching Ni, Cr and Fe plasma strong tolerance, always maintain good growth duringleaching, leaching of Ni, Cr and Fe plasma play an important role.By changing the strain energy type, solid-liquid ratio, substrate concentration, initial pH and direct/indirect contact with multiple cyclic leaching, determine the optimum conditions of biological leaching stainless steel pickling waste residue is: mixed strains; Solid liquid ratio is 6%; Energy substrate concentration is 16 g/L; The initial pH value of 1.0; Cyclic number 10 times.Under the condition of optimization, Ni dissolution rate of 98.2%, 75.7% Cr, through chemical simulation experiment, the dissolution is indirect mechanism of Cr and Fe-biological effect of acid soluble sulfate, and oxidation reduction system of leaching and microbial direct contact no relationship; Dissolve the Ni is indirect mechanism- the outcome of combined action of acid soluble and oxidation.Biological leaching after acid concentration of chromium and nickel can reach 8 g/L and 10 g/L, through a membrane enrichment can achieve 16 g/L, nickel chromium containing 20 g/L, finally through extraction, electrolytic process recycling elemental nickel and chromium elemental.