Next generation metal process development

Pyrometallurgy consumes a large amount of energy and emits C0₂, sulfur, and nitrogen oxides in the process. There is, therefore, a need for new technology that can treat low-grade and complex, non-ferrous metal resources with lower energy consumption and pollutant emissions.

A new hydrometallurgy process, researched by NIRE during the so-called Metal Revolution, attempts to extract only useful metals through water-based processing (Fig.). Since the new process will be carried out at low temperatures and will not emit greenhouse gases and other pollutants, it is considered to be energy-saving and in harmony with the global environment.

Fig:Photo-Leaching

[Materials Processing Department]

Recycling Technology

A resource production and recycling system that discharges minimal wastes is highly desirable with respect to environmental, resource, and energy conservation. Establishment of such a system is dependent on the development of waste-processing technologies having high separation efficiency and low energy consumption rates.

NIRE is pioneering several "Soft Separation Techniques" that involve breaking up a solid waste into its pure materials without dissolution. These techniques include the following:

• Solid-waste grinding techniques that liberate composite materials, such as printed circuit boards and related components, into easily separable pieces.
• Recovery of useful materials from ground solid wastes based on shape.
• Separation of mixtures of plastics and metals based on density in an accelerating flow field.
• Separation of coarse solid waste, such as shredder dust and waste wire, using air flower and vibration transport.



[Materials Processing Department]

Environmentally "safe" chemical treatment of waste plastics must now be addressed if we are to protect the environment and effectively reuse organic resources. NIRE has been actively studying liquid-phase cracking of plastic wastes to produce fuel oil and chemicals from small scale apparatus. Because the typical cracking process lacks hydrogen, the resulting oil contains relatively heavy hydrocarbon fractions and high concentrations of potentially hazardous elements, such as sulfur and chlorine. However, when a hydrogen-donating solvent, such as tetralin or coal tar, is used in liquid-phase cracking of tire almost all organic matter can be converted to a light oil with very low sulfur content (0.5% by weight) under low-pressure of nitrogen. In addition, reaction residues can be used as carbon black for rubber manufacturing. Other recycling technologies, such as dechlorination of polyvinylchloride (PVD), are currently under development at NIRE.

Fig. Boiling Point Disteidution of Oil Products

[Energy Resources Department]

Development of New Materials

"Frontier particles" are functional particles with highly controlled shapes, components and structures. In the optical, magnetic and chemical process fields, the synthesis of new advanced materials using frontier particles is a very attractive and challenging subject. NIRE's main frontier particles research topics are as follows:


• Control of size, shape, components, and structure of fine particles
  
• Surface coating of fine particles with hetero-substances
  
• Highly controlled processing for dispersion and flocculation of fine particles
  
• In-situ and real-time characterization of particles
  
• Synthesis of advanced materials using fine particles
  

photo:Yttrium/Europium Multicomponent Phosphor Particles

[Materials Processing Department]

Thermal plasmas offer a curious reaction environment in which temperature rises up to 10,000K and raw materials are not only rapidly heated but also immediately quenched. Thus, various types of ultrafine particles are easily formed from thermal plasmas and, in some cases, metastable crystal phases appear.

The NIRE laboratory is equipped with both radio frequency (RF) plasma reactors (Fig.2) and direct current (DC) plasma reactors. We have been studying various magnetic ultrafine particles such as nickel metal, iron-cobalt alloy, and Y-Fe-O metastable crystal. Diagnostic and modeling studies are also being conducted.

Photo: RF Plasma Reactor (for UFPs Processing)

[Materials Processing Department]

Siliceous porous materials.

It is well known that porous materials are effective adsorbents for removal of organic pollutants from aqueous or gaseous phases. In recent years, great interest has centered on porous materials prepared from layered compounds such as clays, titillates and zirconium phosphate. NIRE has been studying porous materials based mainly on layered polysilicates and serpentine. We have derived new, siliceous porous materials with high BET surface area (up to 1000m/g), from intercalation of amines and silicon-alkoxides into a layered polysilicic acid (Fig.). Acid leaching of serpentine resulted in the formation of microprobes materials. We are investigating the molecular sieving and catalytic effects of these porous materials.

[Materials Processing Department]

Carbon materials.

Carbon materials can be used as environmentally friendly alternative materials in many fields because they are lightweight and have good electrical conductivity, high adsorptive capacity, and strong affinities to bacteria. NIRE emphasizes research concerning the production and characteristics of carbon materials with various pore structures. These may be used as catalyst supports, in gas separation, and as battery electrodes. Figure 4 shows a carbon material dispersed with fine particles of nickel metal.

Photo:Electron micrograph of Carbon with metal fine particles

[Energy Resources Department]