Grinding kinetics which was a field of active development in the 1960's has become settled for practical applications towards the 1970's. A serious problem was a possible reduction in efficiency for large-scale operations. Research was also extended to the comminution of non-brittle materials including wastes.
Another tide was an intensive research activities in the production of very fine materials. Endless effort is made for the improvement in the efficiency of size reduction. In this context special attention should be paid to the revival of roller mills for the grinding of raw materials in cement production.
Reference is also made to the mill lining techniques, development of the centrifugal mill and the computer control of milling operations.

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Magnetic fluids are very stable colloid suspensions of ultrafine magnetic particles, usually magnetite, covered by surface active agent. A nonmagnetic body placed in the magnetic field under a magnetic field gradient experiences a force which expels the body towards a minimum point of magnetic fluid. This principle can be applied to mutual separation of nonmagnetic materials which could not be separated by using conventional sink and float separation system.
Many application can be thought by using this separation system. Especially the problems in recycling metal scraps have recently increased importance and it is considered to be very useful to separate. nonferrous metal scraps each other. The equipments have been developed by using water based magnetic fluid which can be regenerated easily plus permanent magnets with yoke as magnetic field generator which are lower in price than electro-magnet. This separation system is about to be put into practical application nowadays, as the cost of water based magnetic fluid is decreasing.

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Recently, the high gradient magnetic separation process, which can produce effectively a high gradient magnetic field with a large space efficiency, has been advanced in the fields of magnetic separation. The high gradient magnetic separation, first introduced in 1968 as a means for the removal of very fine magnetic contaminants from clay including not only ferromagnetics but also feebly magnetics, is no longer a new technology. However, the principle of this process, which has been recognized previously, was devised in the high intensity wet magnetic separators (HIWMS) such as the Frantz ferrofilter and the drum separator. Then, applications to a number of solid-solid and solid-liquid separations problems are now being exploited. Recent pilot tests and full-scale industrial installations of high gradient magnetic separators (HGMS) and filters have established their commercial viability and have demonstrated their superiority both in efficiency and cost effectiveness to conventional prior art methods for water treatment and mineral processing.
This paper will address some recent test results obtained by using HGMS in Japan after reviewing the physical principles and structural characteristics of HGMS and HIWMS.

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Complex sulphide ores contained economically metals, however they posed a more difficult mineral processing problem. In recently, the flotation recovery of minerals has significantly been improved by using sulphur dioxide as compared to cyanide. Sulphur dioxide has practically no affect flotation of copper sulphide minerals such as chalcopyrite, chalcocite and bornite, and considerably affect flotation of sphalerite, pyrite and galena. Sphalerite activated copper ions is depressed by using of sulphur dioxide in the presence of zinc or calcium ions. On the other hand, pyrite and oxidized galena is depressed by using of sulphur dioxide alone. Selective desorption of collector on minerals is achieved by control of pulp temperature. In separation of bulk concentrate contained galena and chalcopyrite, galena is selectively depressed by hot conditioning of pulp at 70°C.
The problems of the flotation of sulphide minerals in papers presented at the Complex sulphide ores conference (organized by The Institution of Mining and Metallurgy and held in Rome, Italy, in 1980.) are reviewed.

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The adsorption mechanisms of collectors in flotation of oxide and silicate minerals are reviewed. Physisorption of collectors on the surface of oxide minerals occurs at pH range where the surface is oppositely charged to collectorions. On the other hand, physisorption of collectors on the surface of sheet silicate minerals is complex because the edge of the crystal is oppositely charged to the face of the crystal under certain conditions. In fine particles flotation, chemisorption of collectors helps to improve flotation recovery of oxide minerals. Some examples of chemisorbing collectors is presented. Furthermore, the actions of modifiers in oxide and silicate mineral flotation are discussed.

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In this review the flotation of ions and ultrafine particles has been presented inrelation to the recent experimental and theoretical work abailable.
In the ten years since the experimental work of ion flotation has not been studied. Therefore, the present understanding of the subject is the results obtained in the years 1960-1970. As regards practical application, cadmium and copper ions in waste water had been treated in Japan, but its feasibility has yet to be established.
The physical factors that influence the floatability of fine particle flotation are reviewed. Particular emphasis is placed on the hydrodynamic interactions between particles and bubbles and the dependence of the collection efficiency on the particle and bubble sizes. Dynamic double layer theory studied by Derjaguin and Dukhin has been shown to explain the attachment of fine particles to the bubbles during flotation. Entrainment is shown to be an important contributory mechanism to the flotation recovery of fine particles. The concept of coagulation flotation has been introduced to explain the behavior of effective flotation of ultrafine particles without using of collectors.

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Colloid stability theory was outlined in connection with fine particles processing. It was emphasized that the selective flocculation was essential to mutual separation of fine particles in their mixture. Technical improvements in fine particles flotation were briefly reviewed.

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A number of approaches to the treatment of oxidized copper have been proposed. The principal methods for copper recovery from oxidized are have included leaching, sulfidization flotation, leach-precipitation-flotation, segregation, and leachsolvent extraction-electrowinning. In this paper the basic science and performance of some of the techniques for oxidized copper processing are briefly reviewed. Further, recent trends in the fundamental investigations concerning oxidized copper processing are summarized.

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Recently, the iron mineral processing has been making rapid progress. For instance, the anionic and cationic flotation process, the selective tlocculation-desliming-flotation process and the high intensity magnetive separation were introduced in the iron mineral processing. Many useful reagents for the iron flotation were developed. This paper refers to the main progress of the iron are concentrating process.

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It is reviewed about the recent development of iron are pelletizing technology from the viewpoints of properties of iron are pellet which are necessary for the blast furnace operation.
(1) the relationship between the firing conditions of iron are pellets and their properties
(2) topics of the process of iron are pelletizing
(3) the process of cold bond pellet which has been recently given attention as theenergy. saving technology.

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The art of agglomeration has an important role as a kind of unit operations related to raw material processing and powder treatment. Up to date, the agglomeration has been mainly employed in air. On the other hand, in spite of many advantages, the agglomeration-in-liquid is employed in a limited field because of some technical difficulties.
In order to offer the latest information on principles and applications of the agglomeration-in-liquid, the authors have reviewed about the following items.
(1) Fundamentals.
a) Classification of agglomeration-in-
b) Dominating factors in agglomeration-
c) Agglomeration kinetics.
(2) Agglomeration reagents.
a) Surfactants.
b) Binders.
(3) Agglomeration equipments.
a) Equipments for laboratory test.
b) Equipments for practical operation.
(4) Applications.
a) Size enlargement.
b) Solid-liquid separation.
c) Selective agglomeration.
(5) Examples of practical operations.

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The author at first reviewed briefly the history of process control techniques in mineral processing and then explained its recent 10 years' trend elaborately through observation of the papers concerned, which were presented at the IFAC symposiums, “Automation in mining, mineral and metal processing”, held so far three times. Themain viewpoints of his observation were as follows:
1) mathematical model
2) control theory and practice,
3) sensor,
4) application of computers.
He discussed also the significance and the near future of control in mineral processing plants.

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In the present paper, the following are mainly mentioned;
(1) some methods for estimating the appearance of the accumulation of a particular substance in a closed water-circuit, and (2) the present status of water recycling in mineral processing plants and coal preparation plants.

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A number of studies have recently been carried out in which the abrasive and erosive wear rate of the materials by the mineral grains was determined. In this paper the effects of various variables on these wear are summarized.
M ain contents are as follows:
1) Introduction: Difinition of wear, Classification of wear testing methods- three-body sliding friction between loose mineral grains and materials (flat-flat plate and flat-circle plate), two-body sliding friction between materials and minerals (fixed and loose abrasive), rolling and impacting between materials and loose mineral grains (ball or rod mills), rotating of materials in loose mineral grains, impacting of loose mineral grains against materials and impacting of materials against loose mineral grains-, Relations between different testing methods.
2) Factors influencing abrasive and erosive wear: Knoop and micro Vickers hardness of minerals and materials, Correlationsbetween wear rate W and hardness ratio (material hardness Hm/mineral hardness Ha)-W∝(Hm/Ha) ⁿ-, Wear-resistant factors except hardness- Youngs modulas, tensile strength, fatigue strength, impact strength, etc.-, Effect of mineral grains size while the wear rate are proportional to the grain size, after the critical size (about 10-300 pm) it is almost constant-.
3) Wear characteristics: Initial and steady wear processes-in steady wear the wear rate are proportional to sliding distance or impact time-, Influence of velocity V-W∝ Vn, where n value are 0-0.5 in two and three-body sliding friction testing methods, 0.8-1.3 in ball mill, 2-6.5 in testing methods of impacting of loosegrains against materials (metal: 2-3 and non-metal: 3-6.5)-, Influence of impact angle in erosive wear-the ductile materials exhibits maximum wear rate at low impact angle, but the brittle materials produces its maximum at high angle (for example, rubber: 0°, steel: 15-25°, castiron: 40-50°, glass: 90°).

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In this paper, recent situation, research and development, and future trend on the treatment techniques of steam coal, namely; handling, coal cleaning, coal oil mixture and coal methanol slurry, are briefly outlined on the viewpoint of relevant utilization of energy resources.

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The present review deals with the resource recovery technologies from the solid wastes, that is, municipal solid wastes including bulky wastes and a part of industrial solid wastes, in Japan.
Primarily the authors describe the current status of solid waste generation and its treatment in Japan, and secondarily discuss the recent technological developments in the resources recovery implementation stage or in the stage of demonstration.

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