Solvent extraction applied to refining process for PGMs offers several advantages over the traditional precipitation methods and distillation. Solvent extraction efficiency of Rh and Ru from chloride solutions is very low among PGMs. Therefore, the development of extractants capable of efficiently extracting Rh and Ru is also being studied. However, the current situation is that there are no extractants that can be used industrially. The extraction of Rh and Ru can be improved by forming the extraction-active anion complexes with Rh and Ru by adding Sn (II) to chloride solutions. The authors have previously studied solvent extraction of Rh and Ru with tertiary amine and quaternary ammonium salt from chloride solutions added Sn (II) and shown that the effect of addition of Sn(II) on extraction of Rh and Ru is effective.

In the present study, extractions of Rh and Ru from chloride solutions with 2-ethylhexylamine (EHA), which is a primary amine, and di(2-ethylhexyl)amine [dioctylamine] (DOA), which is a secondary amine, were tested to clarify the effect of addition of Sn(II) on the extraction of Rh and Ru and the stripping of Rh and Ru. The addition of Sn(II) was effective for the extraction of Rh and Ru, however, the stripping of Rh and Ru with solutions of sodium nitrite prepared with sodium hydoxide was low except for Ru extracted with DOA. And also, the extraction of Rh(III) by EHA from chloride solutions without the addition of Sn (II) was high, however, it was found that the stripping of Ru(III) was difficult.

Rice husks include 20 wt% silicic acid, but it is discarded as domestic waste at a surplus biomass of over 200,000 tons per year. The purposes of this study is to use rice husks as a substitute for silica sand and subsequently to make soda-lime glass. For this, we evaluated the effects of utilizing silicic acid from rice husks and optimized their processing to make them suitable raw materials for glass. We succeeded in making soda-lime glass using silicic acid obtained from rice husks and also evaluated its physical characteristics. We made clear soda-lime glass with an amorphous structure by using rice husks after sufficiently reducing their carbon content. However, we found that the glass made from rice husks developed a green color because of Fe from rice husks.

To develop an effective technology for conversion of inorganic arsenic to methylated organic arsenic compounds by using microorganisms, we have searched for microorganisms to have the arsenic methylation ability that are adequately applicable for the detoxification process. As a result, we have isolated arsenic-methylating bacteria Cellulomonas sp. K31.

The growth of strain K31 was also observed in 400 mg As/L arsenic medium. The percent of organic methylated arsenic excreted into the medium by strain K31 showed 91.6% of total arsenic compounds when strain K31 was cultured in the medium containing 5.0 mg As/L arsenic for 4 days. Under this condition Productions of trimethylarsenic oxide and arsenobetaine were 36.1% and 2.5%, respectively. The methylation of inorganic arsenic was evaluated using intracellular extract from strain K31. The result was that total yield of methylated organic arsenic compounds was 57.0% (after 2 h of incubation at pH 6.5 and 40°C), of which trimethyl arsenic compounds accounted for 17.9%. The percentages of methylated organic arsenic compound were the highest value compared to the previous arsenic-methylating bacteria.

Arsenic removal from copper ores/concentrates is one of the most important issue in mining industries. Under the national project led by JOGMEC, Kyushu University and Sumitomo Metal Mining Co. Ltd. has carried out systematic research on the arsenic removal from copper concentrates, including the heat treatment-magnetic separation, flotation and bioleaching. The flotation studies were carried out mainly on chalcopyrite as a main copper sulfide and enargite as an arsenic containing copper sulfide. Enargite was separated from chalcopyrite by flotation by combining potassium amyl xanthate (PAX) and hydrogen peroxide. The resultant arsenic-rich “dirty” concentrates and/or arsenic-containing copper concentrates were subjected to the magnetic separation as well as bioleaching processes. After the heat treatment, chalcopyrite exhibited magnetic property whereas enargite did not. This difference enabled the magnetic separation of the two minerals. Bioleaching was carried out with the addition of activated carbon to improve the copper dissolution as well as As immobilization.

Two-dimensional (2D) analytical assessment of mineral liberation from ore particles, such as scanning electron microscope and energy dispersive X-ray (SEM/EDX)-based analysis of particle sections, results in stereological bias compared to the actual three-dimensional (3D) mineral liberation. Thus, a simulation-based stereological correction method for accurate assessment of mineral liberation was developed. The method utilizes a pre-established database of numerically simulated binary particles to estimate 3D composition distributions based solely on measurable 2D composition distributions. Notable features of the method include the relatively small amount of 2D-distribution input data required, and the rapidity of the analysis. The method is also suitable for post analysis of SEM/EDX-based particle sectional liberation analysis.

The discrete element method (DEM) is widely used as a simulation tool that can quantitatively reproduce the behavior of powder in several industrial processes. To reproduce a grinding process such as the high pressure grinding roll (HPGR) with DEM, it is necessary to combine it with a particle breakage model that directly calculate particles breakdown. In this paper, an example of HPGR simulation by DEM coupled with T10 model, which is one of the particle breakage models, was introduced. DEM simulations suggested that crack growth and liberation in HPGR might be related to the impulse, which is the product of the stress and time received by the particles.

BBP (Biodegradable/Bio-based Plastics) should be managed independently of general plastics during and after their use. However, in reality, it is difficult to put a clear line between their uses. In the case of the event that BBP is mixed in other plastics, it is necessary to thoroughly consider its effect. Experimental results of wet sink-float separation between PHBH, which is one of the BBP, and PE/PET showed good separation performance. Mechanical properties of recycled PE/PET were not significantly affected by the contamination of 1% PHBH. However, since the data on the physical separation for BPP is insufficient in the world, it is necessary to continuously study the influence of the shape and surface properties for reliable plastics circulation.