For the sustainable development of our society, the energy-saving and low-emission processes for the production and utilization of metals are highly desired. One effort being made in establishing such environmentally friendly metal production technologies (soft metallurgy) is the development of a surface finishing process with no sludge generation. Nearly all the components can be reused by subjecting the waste solutions to on-site advanced treatment using a new solvent extraction method and other means to separate and purify each metal and complexing reagent. This technology will replace the current waste solution treatment which generates a large amount of sludge. There are significant expectations for the development of this technology because it will solve many sludge-related problems including the discharge of toxic metals and the need to secure dumping sites.

Recycling of municipal and industrial wastes will no doubt continue to be pursued in various ways. An important consideration in waste recycling is minimizing the energy consumed by recycling and the additional environmental burdens (such as exhaust gases and effluents) that arise from recycling. For this reason NIRE is undertaking the development of efficient waste separation technologies. We are applying dry separation methods, which do not require wastewater treatment processes, to the sorting of coarse particles of metals and plastics and working to increase the efficiency of dry separation. For fine particles we are using wet methods, which offers highly precise separation, and our efforts in this case include minimizing the amounts of chemicals added for separation, and investigating separation methods that use functional agglomeration nuclei to eliminate the use of chemicals altogether.

Because of the hardening property of thermosetting resins such as phenol and epoxy resins when heated, converting them to oil is impossible with treatment methods such as simple pyrolysis. Therefore it is in fact not done. Some of these manufactured resins which mixed with metal, glass, and other materials are subjected to material recycling after use, but at present the rest are landfilled as specified industrial wastes. Owing to the emergence of landfill site shortages and environmental problems, there has been a pressing need for the development of treatment methods; that need was answered by the liquid-phase cracking method developed by NIRE, which achieves an oil conversion rate of virtually 100%, and a recovery rate of 50-80% as monomers. Accordingly, there are expectations that this method will create a closed, zero-emission industrial system.

In a recycling oriented society it is necessary to minimize the environmental load that comes with the manufacture and cycling of materials and products. One way of addressing this is construction of a social system based primarily on reuse. Such a recycling oriented society needs technologies for evaluating and judging the recyclability of materials and products. NIRE is researching an ultrasonic technology that is capable of safely, and easily evaluating the degradation and reusability of materials by non-contact. This method accurately judges and identifies damage inside materials based on dependence of wave propagation on physical properties of materials, which are associated with the various modes of the elastic waves arising under the ultrasonic irradiation. NIRE is working toward the application of this technology in judging the recyclability of materials used in electronics, information, and other areas (see figure at left). And we are developing a new method for assessing the environmental impacts of materials.

As part of our efforts toward the most effective use of valuable rare metal resources, NIRE is conducting research on the creation and manipulation of high-performance fine powders with new functions. An interesting challenge as we move into the 21st century is the manufacture of materials with new functions by taking advantage of the fascinating characteristics of these fine particles.

• Liquid-phase synthesis of rare earth fine phosphor particles and long persistence phosphor particles
• Plasma synthesis of ultrafine magnetic particles
• Micromanipulation of fine particles using laser radiation pressure

Porous materials with molecule-sized pores are useful as adsorbents and catalysts not only in industry, but also in environmental protection. The intent of this research, which is part of our research on Silicate Technology, is to develop new siliceous porous materials by exploiting the heat resistance of SiO₂ to replace some of the Si in a silicate framework with other elements. The figures at right illustrate how we use the ability of layered polysilicic acid (a) to form organic material in an orderly configuration between layers, resulting in an organic/inorganic composite (b), which leads to formation of a porous material pillared with metal oxides of Si, Ti, and other elements (c), thereby providing new porous family 1 nm wide and 1.5 to 5 nm high. This method can be used on layered compounds that have transition metals in layer lattices, and also finds application in the synthesis of porous silica materials with a high Ti content. This research has advanced into the use, as useful materials in environmental protection, of siliceous porous materials with hierarchical structures that have at least two different scale length orderings, ordered mesopores in nanometer scale and ordered morphogenesis of shapes in micrometer, as well as the spherical porous materials in (d).

Carbon materials hold promise for a wide variety of applications as environmentally friendly materials because they are lightweight, have good electrical conductivity, excellent adsorptive capacity, and a strong affinity for bacteria and other microorganisms.

NIRE is using a variety of organic resources as materials for making catalysts, adsorbents, porous carbon suitable for gas separation agents, molecular sieve carbon, and other materials for environmental remediation, and investigating their characteristics. The photograph at right shows the coexistence in carbon of fine titanium oxide particles, and pores several nm in size. This carbon can likely be used in new catalytic reaction applications.