Since 1973, the oil crises have deeply influenced to the zinc industry in the world. In order to overcome a rise in energy cost, Iijima electrolytic zinc refinery has carried out various improvements for plant modernization and energy saving. Extensive application of the computer control system to the plant operation is a typical example.
In 1984, Fujitsu's super mini-computer (S-3500) was installed, and the “Akita Zinc Refinery Total Information Control System” abbreviated to “ATICS” was developed for the pursuit of more effective operation in the plant and administration in the office. From 1985 to 1987, Yokogawa's digital control stations (CENTUM) were installed to replace the analog instruments in the field control rooms. The combination of the field side digital control stations and the host computer has brought not only the effective reduction in labor and energy cost, but also the significant improvements for stable plant operation.
This paper presents a summary of the Factory Automation System and the Office Automation System at Iijima Zinc Refinery, including the effectiveness of the several automatic process controls as an example.

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Copper smelting capacity in Japan was quickly expanded in line with remarkable economic growth in late'60s to early'70s. Annual copper concentrate requirement was also trippled during this period compared to the previous decade.
Under these circumstances, with increment of high impurities in copper concentrate processing amount, impurity elements input to a copper smelting complex such as As, Sb, Bi, had been increased not only from the stand point of quality but also the processing volume.
Arsenic in copper concentrate is basically distributed to process exhaust gas and copper anode. Most of arsenic which was distributed to gas phase was fixed as arsenic sulfide and piled up, and the remaining arsenic in anode was fixed as copper arsenide during purification stage of electrorefinning, though some part was recycled in complex.
Sumitomo Metal Mining has made many R & D efforts to recover and separate arsenic from the process to cope with the growth of arsenic input to the complex.
As a result of these R & D works, Sumitomo developed original process to start a commercial production of copper arsenate in 1971. In 1973, arsenic trioxide was also started to produce in a perfect hydrometallurgical way. Finally, Sumitomo succeeded in establishing to the purification technique of high purity arsenic metal from Arsenic trioxide.
These series of technical developments, Sumitomo accomplished the stable operation of copper arsenate, arsenic trioxide, and commercial production of high purity arsenic metal.
In actual design and operation Sumitomo paid close attension to safety, hygiene, and cleanness of the plant to prevent arsenic exposure to workers, and solved these problems.

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The class II behavior was investigated by both numerical simulations and experiments, and the following results were obtained.
Firstly, class II behavior was presented by a spring model which consists of two tandem connected sheaves of springs with different strength, which is assumed to follow the Gaussian distribution. In the pre-failure region, spring elements fail similarly between the two sheaves, but failure concentrates on one of them after the strength failure point. And the smaller the coefficient of variation of strength, the severer the concentration of failure. Such a mechanism, that is to say, failure concentration may lead to the class II behavior as Hudson [17] has illustrated with simple diagram.
The FEM stochastic model also showed that smaller coefficient of variation of strength leads to class II behavior, much similar to the result obtained from the spring model. And the FEM stochastic model also showed that end-boundary condition and/or hight-to-width ratio have little influence on the shape of stress-strain curve.
Secondly, experiments showed that stress vs. recoverable-strain curves of the all tested rock samples have a positive slope in the post-failure region, under either uniaxial or triaxial compression. And it is found that an important difference between class I and class II behaviors is the difference of permanent deformation.So class I rock samples have large permanent deformation and class II rock samples have small one.
Because numerical models used in this study considered only elastic deformation, they can only give an excellent approximation to the behavior of such rock which shows class II characteristics and has a minor permanent deformation.

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This report describes discussion for anisotropic dependence of rock elasticities in stress evaluating based on the behavior of borehole deformation under stress relieving by overcoring. Pre-overcoring stress and relieved stress were calculated on measuring displacements and strains using anisotropic and isotropic equations. Obtained results and knowledges on them are summarized as follows.:(1) Diametral displacements in Inada granite behave anisotropic with significant difference of elastic modulus. E₁=47.0GPa; in X direction parallel to rift plane E₂=58.6GPa; in Y direction normal to rift plane
(2) The influence of pre-overcoring appears as the maximum compressive stresses up to 2.2MPa at a distance of about 20mm from the bit surface.
(3) Anisotropic evaluation of relieved stresses becomes a useful method for Inada granite on the basis of comparing calculated results with experimental results for stress condition.
(4) Relieved stresses calculated on measuring strains are seen to be from 1.20 to 1.35 as great as that experimental condition. Therefore, it is suggested that elastic properties on strain are greater than that on displacement

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The authors investigated core discing with a center hole often encountered at the overcoring around a previously bored small hole in highly stressed rock, from observation and stress analyses. The following results were obtained:(1) Core discing with a center hole occurs under the lower in situ stress than the stress under which core discing with no hole occurs.
(2) If the thickness of a hollow core becomes the thinner, core discing occurs under the lower in situ stress. Therefore, the occurrence of core discing can be controlled by the choice of inner and outer diameter of a hollow core.
(3) Main fracture of core discing with a center hole is caused by tensile stress in rock near a boring bit. This tensile stress develops when in situ stress component in the boring direction is high.
Moreover the authors analytically determined the criterion on in situ stress condition under which core discing with a center hole occurs, and compared it with the three dimensional stress condition measured where this phenomenon really occurred. It was confirmed that both were consistent with each other

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Boring tests were made using coal specimens applied external loadings and the results were compared with field observations at the actual coal seam boring.
Field data of actual coal seam borings can be classified into some patterns according to the weight change behaviour of cuttings and occurrence position of jamming. Similar patterns were also found in the results of the laboratory tests.
Abnormal increase of cuttings and occurrence of jamming that are occasionally experienced in coal seam borings are mainly caused by the fracture of coal around the borehole. Therefore the test boring technique that has often been adopted to investigate the high stress region in coal seam is a reasonable method.
During actual boring operation, it would be able to give an approximate estimate of the mode of fracture in the coal seam by monitoring the weight change of cuttings and occurrence position of jamming.

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With increasing industrial applications of the method of the transporting settling slurries, a better understanding of the mechanism of the slurry flow at lower velocities has become essential. Below the critical deposition velocity V_d of flow, the deposition of solid particles occurs on the bottom of the horizontal pipe. If the deposited particles are sufficient, the plugging of the pipeline can be induced through the large surge of flow or the sudden change of flow conditions, such as a rise in concentration or a drop in velocity V. However, some papers confirm the possibility of the stable flow configuration in pipe despite of a stationary bed.
One of the main problems in the hydraulic transport for V < V_d is the assessment for bed thickness h and hydraulic gradient i_m. The accuracy of one of the factors is interdependent upon that of the other. Since the correlations have been basically proposed by empirical methods, the bed thickness cannot be reasonably well predicted with flow conditions.
The purpose of this paper is to derive the general correlation which determine the relationships between the bed thickness and the corresponding flow condition, and to give the procedure for the pipeline design with the aid of the authors' previous results. Based on the concept of the suspension behavior introduced by Bagnold, this paper estimated the normal stress on the particle at the surface of the bed. The flow condition of initial motion of the particle, then, was considered, and thus these theoretical analyses made possible to present the general correlation of h and to simulate the slurry flow for V<V_d. Experimental values obtained were fairly well coincided with the predicted values.
The results of this study may be summarized as follows:(1) For a given system and particle properties the Froude number, Fr V/√4gR, is approximately as a function of concentration alone, such as Durand's results for 0.2<hr <0.6, in which hr is the ratio of the bed thickness to the pipe diameter.(2) The predictions for the critical deposition velocity V_d agree with those by Durand for particles greater than 2mm, while for ones less than 1mm both predictions are incompatible with each other, when the equivalent thickness d_e/2 is substituted for the bed thickness at the initial condition of V_d.(3) The relationship between hydraulic gradient and slurry velocity, which is the im-V cure predicted, shows that the critical velocities are always less than the critical deposit velocities, and considerable care, therefore, should be exercised to determine the practical velocity in the pipeline design.

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A new concept of a continuous reduction process for titanium production was discussed and experimentally verified. The new process employs molten alloy system containing titanium, zinc and magnesium. TiCl₄ is injected into the molten alloy to be reduced by magnesium in the alloy. By using TiCl₄ injection technology, the reduction process of high efficiency, which has following two advantages, was developed. 1) The reduction reaction can be carried out even in such a condition that magnesium content in the molten alloy is not higher than one percent. 2) Titanium production rate is increased to the level much higher than that of batch Kroll process.

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The general expressions for Raoultian activity coefficients in quaternary regular solutions have been derived. These equations allow calculation of activities as function of slag composition and temperature, provided six interaction energies are known for six constituent binary systems. The interaction energies for three binary solutions of the CaO-FeO, CaO-Fe0_1.5 and FeO-Fe0_1.5 systems have first been assessed, and the activity values of CaO (s), Fe_0.960 (1) and Fe01.33 (s) have been calculated for the CaO-FeO-Fe0_1.5 slags. They are in good agreement with the experimental data. The interaction energies in the binary oxidic solutions of the MeO-CaO, MeO-FeO and Me0-Fe0_1.5 (where MeO =Cu0_0.5, CoO, NiO, PbO, ZnO) have then been estimated from the heats of formation of binary compounds, liquidus curves, or terminal solid solubilities. The activity coefficients of minor oxides are then calculated at infinite dilution in ferrite slags, and compared with experimental data at 1523 K.

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The dilute dissolution of monovalent and divalent cationic elements in S-bearing ferrite (thio-ferrite) slags has been studied theoretically on the basis of the Flood-Førland-Grjotheim (FFG) model for ionic salts. The overall dissolution of a minor element in S-bearing slags may be regarded as consisting of two independent sulfidic and oxidic fractions, both of which have been mathematically defined based on the FFG theory. Minor elements thio-ferrite slags can be classified into three categories:(1) the solubilities of Ag, Au, Pd and Pt may become several hundred times higher in thio-ferrite slags than in S-free slags, (2) the dissolution of Co, Ni, Sn, Mn, Mg and Be is almost exclusively oxidic, and their activities are not affected by the presence of a few percent sulfur, and 3) both oxidic and sulfidic solubilities are equally important for Cu, Pb and Zn.

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In this investigation, zinc sulfide has been sulfation roasted in the closed reactor where the materials involved in the reaction are conserved and the reacting gas is being circulated. In this closed reacting system, the atmosphere for zinc sulfate formation is being gradually produced as shown in phase stability diagram calculated by thermodynamic analysis coupled with material conservation in the system. The zinc sulfate formation has been shown to take place in the following sequence: ZnS→ZnS→ZnO·2ZnSO₄→ZnSO₄, which is in agreement with thermodynamic prediction. However, it has been discussed and could not been clarified whether the formation of these intermediate compounds take place within the particle or not.

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