This paper described about the selective recovery of anatase concentrate and hematite concentrate from ilmenite concentrate. The ilmenite concentrate was dry ground to -200 mesh with pebble ball mill. After coal and salt, coal and ferric chloride and coal were mixed to the ilmenite concentrate, those were made pellets. The pellets were roasted with reduction gases generated in situ from the coal admixed the ilmenite concentrate. After that, the roasted pellets were wet ground to -200 mesh with porcelain mortar and leached with 6.0 mol/dm³ of H₂SO₄ for 15 hours at 97°C. Anatase and hematite concentrate were collected from the leach liquor by two processes. One process was the collection of anatase concentrate from the leach liquor. Another process was the collection of hematite concentrate from filtrate of anatase concentrate that was collected. In the former process, Ti⁴⁺ ions in the leach liquor were reduced to Ti³⁺ by keeping to ORP=-180--200 mV and pH=0.6-0.7 with metallic magnesium and then anatase concentrate of 52.3%Ti was obtained with 93% of recovery by being oxidized for 2 hours at 97°C. In the latter process, Fe³⁺ ions in filtrate that collected Anatase concentrate were reducd to fe²⁺ by keeping to ORP=-180--200 mV with metallic iron. After that, in order to collect hematite concentrate, using ozone as oxidant, those ions were oxidized by keeping to ORP=+450-+500 mV and pH=3.20-3.30 and hematite concentrate of 70%Fe was obtained with 99% or more of recovery.

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The leaching of steelmaking dust with sulfuric acid and hydrochloric acid has been conducted, and its kinetics has been studied. High grade steelmaking dust of under 200 mesh were treated to extract metals under several conditions, and leaching percentages of zinc, iron and lead were investigated. The results are summarized as follows.
The extraction percentage of iron is less than 10% even when zinc is leached out about 80% by the weak leaching condition. The leaching percentage of iron largely depends on leaching conditions such as acid concentration and leaching temperature.
The extraction percentage of lead is very small in the sulfuric acid, while lead is preferentially leached in the hydrochloric acid. This fact may be attributed to the difference of lead solubility in each acid.
The leaching rate obeys the logarithmic function rule, which is expected to the volume reaction model.

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The influence of sulfur dioxide addition on dioxins generation and decomposition behaviors has been evaluated by thermodynamic equilibrium calculations. The calculation conditions in this work were as follows: (1) the C-H-O-Cl quaternary system has the ratio of [C : H : O : Cl]=9 : 6 : 4 : 1, i.e. this system corresponds to the most typical generation region of dioxins, (2) total amount of respective elements (N_C+N_H+N_O+N_Cl) is 1 mol, (3) sulfur dioxide is then added to this C-H-O-Cl quaternary system and (4) total pressure and temperature range were 1 atm and from 773 to 1773 K. The influence of sulfur dioxide addition is shown to change the oxygen potential, on which the dioxins generation and decomposition is independent, i.e. higher temperature and higher oxygen potential lead to dioxins decomposition. The essential effect of sulfur element is shown to reduce hydrogen chloride potential, leading less dioxins chlorination reaction.

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Resources recycling is necessary for the sustainable society in the 21 century. Smelting or refining companies in Japan have treated non-ferrous metal scraps for many years and commenced wastes treatments about three decades ago. Their technologies and facilities are available for treatments of wastes bearing a few of non-ferrous metals because they have many experiences of extracting dilute non-ferrous metals in mineral resources.
Virgin non-ferrous metals and their scraps are used for wires, batteries, platings or secondary raw materials of virgin non-ferrous metals etc.. Recycled non-ferrous metals, i.e. virgin metals refined from scraps account for 10% to 45% of total each new non-ferrous metal refined in Japan. It is estimated that a content of a non-ferrous metal in secondary raw materials treated in smelters depends on a price of the virgin non-ferrous metal.
And, the amount of wastes treatments and non-ferrous metal recoveries from wastes in 2000 increased compared with 1999.

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