A series of investigation on concrete support combined with outer and inner steel sets, which was developed at Matsumine mine, a mining section of Hanaoka mine, Dowa Mining Co., to maintain the haulage drift in the heavy pressure zone, are being carried out in order to clarify the mechanism of the support. In this paper described was the influence of mining excavations of black ore deposits at the upper levels on the strains and internal forces in the support at the lower haulage level as a result of long-term in-situ measurement for more than three years.
Before the beginning of mining excavations, hydrostatic secondary rock pressure which was caused by the reaction of the rigid support against the deformation of surrounding soft rock mass was found to increase approximately at the rate of 0.07-0.08 kg/cm²/day or about 27 kg/cm² /year. Therefore, it is very important to plan the mining excavations so that it may be completed before the support of the haulage drift fails due to this hydrostatic secondary rock pressure.
Once mining excavations of so-called “60m” section began at the upper levels of the haulage drift, considerable unloading of rock pressure around the drift occurred because the mining section is located in the direction of principal rock pressure, and, at the same ti me, the direction of rock pressure around the drift was rotated towards the un-mined area. However, as mining of so-called “No.47” section located at the upper levels ahead of the measured point progressed, internal forces in the supportb egan to increase again because of the stress concentration caused by the mining excavations, and it continued until the mining of lower level of “60m” section began. Rock pressure around the haulage drift was definitely unloaded finally by the mining excavations right above the measured point of the drift.
Thus, in-situ measurement on the strains and internal forces in the concrete support combined with outer and inner steel sets were successfully fulfilled until the role of the lower haulage drift was almost accomplished.

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An electric probe for measuring local velocity of particles in solid-liquid mixtures has been constructed and tested for its performance using four kinds of glass spheres, sand, and an oxidized iron powder.
The probe is composed of a supporting bakelite tube (dia. 4mm), a ceramic tube, and three ringlet electrodes made of Pt wire (dia. 0.3mm).
The electrodes are axially placed on the surface of the ceramic tube at intervals of 10mm.
The fluctuations of differential voltage between the middle and the upstream electrode were cross-correlated with those between the middle and the downstream electrode to determine the transit time in conjunction with the local velocity of particles.
Volumetric flow rates calculated from particle velocity distributions of upward flows in a vertical pipeline were compared with those obtained from an electric magnetic flow meter.
The accuracy of 6% in the sand and the glass sphere and 8% in the oxidized iron powder was achieved at the discharge velocity of about 3m/s.
A comparison of velocity distributions between the probe and the pitot tube in a horizontal pipeline revealed that the pitot tube measurement was insufficient in the region of high solid concentration.
Some difficulty was encountered in the measurement of velocity distributions in a steel pipeline due to the electric effect of the steel pipe. It was, however, solved by means of isolation amplifiers introduced into the measuring system.

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Applicability of dissolved air flotation (pressure type flotation) for separating ultrafine particles has been investigated using barite-quartz and calcite-quartz mixtures as samples.
In pressure type flotation of barite-quartz mixture, good separation is obtained by the addition of smaller amount of sodium oleate as a collector than in dispersed air flotation (Denver type flotation). On the other hand, in pressure type flotation of calcite-quartz mixture, it is difficult to make calcite selectively float from quartz by adding sodium oleate. This may be explained by the reason that heterocoagulation of calcite and quartz particles can not be prevented under a comparatively static condition in pressure type flotation. However, the separation of calcite from quartz by pressure type flotation is possible when selective flocculation of calcite is achieved by using a polymeric flocculant (Separan AP30) with a dispersant such as sodium hexametaphosphate. The separation of barite-quartz and calcite-quartz mixtures by pressure type flotation is accomplished only at low pulp density below 2 to 3%.

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Grinding experiments were made on a new type of ball mill operated under centrifugal force. Three samples of feldspar. quartz and soda glass were utilized to examine the specific surface area and size distribution as a function of operating conditions.
Specific surface area measurements demonstrated that a grinding rate equation previously proposed for a feldspar sample was also validated for quartz and soda glass as well as different feldspar samples.
Size distributions of products produced under the suitable conditions of fractional ball and powder fillings were found to be represented well by Rosin-Rammler equations. It was also found that the size distribution was correlated well with the sum of additonal grinding energy.

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Lithium adsorptive properties of γ-manganese (IV) oxide (γ-MnO₂) were studied using dilute lithium chloride solution and actual geothermal water. The results are summarised as follows;
1) The lithium adsorption is relatively slow; 6 days were being required to be in equilibrium at 80°C.
2) The lithium uptake increases with an increase in pH of the solution. The selectivity series is K=Na<Li<Ca at pH below 9.5 and is K<Na<Ca<Li above 9.5.
3) The lithium uptake by r-MnO2 is independent of the adsorption temperature (5-80°C). The lithium uptake is scarcely influenced by the presence of the coexisting salts such as NaHCO₃ (30 mM), Na₂SiO₃(30mM), KC1 (5mM), Na₂B₄O₇(4mM), CaCl₂ (3mM), Na₂SO₄(3mM), KBr (0.5mM), Na₃AsO₃ (0.5mM), Na₃AsO₄ (0.5mM), or BaCl₂ (0.4mM). The lithium uptake slightly decreases in the presence of 100mM sodium chloride.
4) The lithium thium uptake from the geothermal water (C_Li=5.2ppm, pH 8.3) is above 70% in a case of 20mg adsorbent per 1cm³geothermal water.
5) The γ-MnO₂is scarcely soluble (10-6M) in the solution from pH 3.5 to 10.8 and in the actual geothermal water at 80°C.

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The equilibrium between molten copper and the alumina-saturated Na₂O-Cu₂O or SiO₂-Cu₂O slag was studied at 1250°C, and the distributions of As and Sb were also investigated. The results are as follows:
1) The activity of CuO0.5 in the basic slag of Na₂O-Cu₂O deviates negatively from the ideal solution. This behaviour is similar to the activity of CuO0.5 in the acidic P₂O₅-Cu₂O slag.
2) The activity of CuO0.5 in the alumina-saturated SiO₂-Cu₂O slag deviates positively as in the iron oxide-base slag, such as FeOn-Na₂O, FeOn-CaO and FeOn-SiO₂ slags.
3) The distribution ratios of As and Sb between the slag and molten copper are not affected by addition of SiO₂ to the Cu₂O melt. In the case of Na₂O, the distribution ratios of As and Sb largely increase with the content of Na₂O in slag. Therefore Na₂O is a good flux for the removal of As and Sb from the crude copper.
4) The distribution ratio of As is more strongly affected by slag basicity than that of Sb is.

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The behavior of such impurity as Ni, Co, Fe, Ag, Cu or Cd in the electrowinning of zinc was studied. The characteristics of iron-group metals, compared with other impurities, were revealed in the impurity content of the deposits as well as its deposition rate, although the impurities studied brought about more or less higher critical current densities above which the massive zinc deposition occurred.
The SEM images of the deposits obtained from the baths containing iron-group metals were similar to that of pure zinc, while Ag, Cu and Cd affected the morphology of the deposits in a striking manner. The presence of iron-group metals in the solutions, further, resulted in the distinct pattern of the potential oscillation caused by the deposition and dissolution of cathode zinc. These phenomena were in good agreement with the deposition behavior of each impurity.
Thus, it may be necessary to distinguish the iron-group metals from other impurities in the dicussion of impurity effects in zinc electrowinning.

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