Coal measure rocks in Japan tend to deteriorate their mechanical properties by the presence of water. Most rocks around roadways and workings in the coal mines are liable to be exposed to water from the strata and other sources. Therefore, knowledge of the effect of water on the mechanical properties of coal measure rocks is of great ignificance for strata control in coal mining operations such as the maintenance of roadway and the face support and for the utilization of these rocks as back filling materials.
In the present paper durability of coal measure rocks for water is investigated by means of three different kinds of slaking tests. The practical applicability of these tests to coal measure rocks is discussed and the contributory factors to slaking and their correlation with other properties such as uniaxial compressive strength and montmorillonite content are also investigated.

抄録全体を表示

Measurements were conducted to clarify the air flow characteristics in vinyl air ducts when they are used for forcing ventilation. The results of the investigation are summarized as follows:(1) The pressure loss depends greatly on the deformation of cross section of the ducts, especially that of the outlet.
(2) The velocity distribution in the ducts are easily disturbed by the irregularity of cross section of the ducts.
(3) The friction coefficients range between 0.015 and 0.05 in usual condition of air flow rate, depending on the kind of duct and whether the cross section is deformed or not.

抄録全体を表示

The authors have studied on the slug flow of air-water mixtures flowing upward. In the 3rd and 4th reports, the flow characteristics including gas slug velocity, gas slug length, liquid slug length, void fraction profile and liquid-phase profile in the liquid slug region were investigated. In this report, the statistical characteristics of static and differential pressure fluctuations were discussed theoretically and experimentally.
The probability density functions (PDF) of the pressure fluctuations are bimodal in the case where the segment of measurement is shorter than gas slug length, and the profiles of PDF are unimodal in the case of longer segment than gas slug length, in general. The power spectral density functions (PSD) of the pressure fluctuations have some maximal and minimal values and decrease with increasing frequency. The frequency of the first minimal value of PSD is given by Eq.(29) approximately. The same results for PSD were obtained from analytical considerations.
The static and differential pressure fluctuations were simulated by means of Monte-Carlo method, and the PDF and PSD of the simulations were verified by the experimental results.

抄録全体を表示

The mill concerned consists of a shallow cylindrical container vibrating in a horizontal circular path and a disc-shaped grinding body whose thickness is slightly smaller than the depth of the container. In this mill the breakage of material is carried out mainly by compressive stresses caused through the friction between the grinding body and the wall of the container. In certain vibrating and frictional conditions the grinding body moves rotating along the wall of the container in the opposite to the driving direction. The product of the frictional force between the grinding body and the wall of the container and the relative displacement of the grinding body is considered to contribute to the grinding efficiency. That is, the work performed through the movement of the disc should be proportional to the product of the angular velocity of the disc and the third power of the disc radius. The authors introduced an expression to calculate the angular velocity of the disc as a function of vibrating and frictional conditions as well as the mill dimensions to be used. An optimum disc radius with regard to the best grinding efficiency has been also discussed but the slippage degree of the disc has been assumed to be independent on the disc radius.
A series of grinding tests with reference to the performance of grinding body has been undertaken using four discs with different radii, the driving unit and the container of a laboratory type disc-ring-vibration mill.
The results of the grinding tests on quartz as grinding material have verified essentially our view on the performance of grinding body, but some disagreement has been found at the largest size of the grinding body. And the cause of this disagreement has been also discussed.

抄録全体を表示

Separation of white colored pottery stones from wasted parts such as finer size than 5mm by using a color sorter was investigated.
The results obtained are as follows: 1) Sizing of sample by sieves as pretreatment and suitable adjustment of sensitivity for each particle size range were necessary for the separation with high efficiency.
2) The process of removing of little contained parts such as dark colored stones was effectual, because a number of air jet ejection and consumption of compressed air can be reduced.
3) In the case of so large feed rate which particles formed a line compactly on the belt, the posibility of incidental removal rate of useful pottery stones by air jet ejection increased. Therefore, feed rate was desired to be about one third of calculated one under the condition of the particles forming a line compactly.
4) The sample coarser than 0.6mm could be separated by color sortor.
5) The sample of particle size ranged from 1.2 to 2.4mm, containing about 80 wt% of white colored pottery stones, could be saparated at about 70% in the Newtonian separation efficiency. In that case, the maximum feed rate was about 5 kg/hr.
6) It was thought that the separation of Amakusa pottery stones by the color sorter could be applicable to industrial process, because the concentration of high-grade pottery stones could be obtained.

抄録全体を表示

The flotation separation of dickite and quartz finer than 2 μm has been investigated by using a pressure type and a Denver type flotators. Flotation tests were carried out by activating dickite with calcium chloride, followed by adding sodium oleate as a collector.
In Denver type flotation, the separation of dickite from quartz can be achieved by the addition of large amounts of calcium chloride and sodium oleate, in neutral pH region. However, in the case of pressure type flotation, dickite can be seiectively floated from quartz by adding Separan AP30 (an anionic polymeric flocculant) and sodium oleate in the presence of proper amounts of calcium chloride at pH 5 to 12. The amounts of calcium chloride and sodium oleate necessary for floating dickite in pressure type fiotation are one tenth and one fortieth, respectively, of those in Denver type flotation.
The amounts of calcium ions adsorbed on dickite are larger than those on quartz in neutral to weakly alkaline pH region. The lower the calcium concentration is and the lower the pH value is, the more remarkable the difference in calcium adsorption between dickite and quartz becomes.
It is considered from the above results that in pressure type flotation dickite is selectively floated from quartz by the following mechanism: preferential adsorption of calcium species on the dickite surface occurs on the addition of proper amounts of calcium chloride in moderate pH region and induces the adsorption of Separan AP30 and oleate ion by which dickite flocs are formed and the surface becomes hydrophobic.

抄録全体を表示

The converter residue, which is formed in the copper-making stage and mainly composed of partially melted Cu₂O-FeO_n or Cu₂O-FeO_n-SiO₂ base slag and crude copper entrained in it, causes some serious problems in the converting operation as well as the elimination of minor elements. The present study aims at originating a process that enables the treatment of this residue by reforming it to fully melted CaO-FeO_n-Cu₂O or CaO-FeO-Cu₂OSiO₂ slag by adding CaO flux.
The phase relations in the CaO-FeO_n-Cu₂O system were investigated at 1200-1300°C in air or argon gas atmosphere, and it was clarified that a considerably wide miscible region existed in the range of high Cu₂0 concentration. When 7.5 or 15 wt% SiO₂ was added to the CaO-FeO_n-Cu₂0 ternary system, a two-liquid region, along with the miscible region, appeared in the range of high Cu₂0 composition, and it was considered that the formation of a double oxide, 2CaO-SiO₂, resulted in the miscibility gap. The phase relations in the CaO-FeO_n-Cu₂O-7.5% SiO₂ slag in equilibrium with copper metal as well as the distribution ratios of minor elements between the both phases were determined at 1200°C. The phase relations did not much differ from those obtained under a condition without copper metal. The distribution ratios, Lxs/c, at Po₂=4×10^-5 atm are 7, 8, 1.5, 45 and 600 for arsenic, antimony, bismuth, lead and zinc, respectively.
It might be concluded from the present study that the converter residue can be melted at around 1200°C by adding CaO flux to as much as 10 wt%, and that a significant improvement in the elimination of minor elements can be expected by discharging the melted residue out of the converter.

抄録全体を表示

The effect of anode bismuth level and of concentrations of dissolved oxygen and bismuth ions in copper electrolyte were investigated to understand the formation mechanism of anode slime layer and its influence toward passivation behaviour. The metallic granular forms of bismuth were found in the anode at the lower bismuth content. However, the higher bismuth content of anode exhibited a hairy or meshes-like shape. The bismuth dissolved preferentially during electrolysis and the anode surface after electrolysis became excessively uneven. The slimes were classified into the adhering and the falling types. The amount of falling slimes was about 90% of total slime formed and it mainly consisted of copper powder mechanically separated from anode. On the other hand, the adhering slimes consisted of copper powder, Bi₂O₃ and Bi₂ (SO₄)₃. The copper powder in the adhering slimes was the fine particles formed by the disproportionation reaction of Cu⁺ ions. Bi₂(SO₄)₃ in the slimes were precipitated by the supersaturation of dissolved Bi³⁺ ions and observed in the inside of grain boundary.
Under the electrolytic condition of high current density and in the case of the addition of Bi³⁺ ions into electrolyte, layer of needle-like precipitates of Bi₂ (SO₄)₃ was observed on the adhering slime. This slime layer caused the anode to passivate sensitively.
When Bi, As and Sb impurities were coexisted in the copper anode, the composition of the resulting anode slime was Bi₂O₃, BiAsO₄ and SbAsO₄.

抄録全体を表示

In leaching of nickeliferous oxide ore, such as, Garnierite with H2SO4 solution Mg, Fe, Al and Mn etc. are dissolved out, besides Ni from the ore.
A series of fundamental experiments were carried out on the separation and the recovery of Ni from the pseudo-sulfuric acid leaching solutions.
In this paper, the effective factors for the recovery and the separation of Ni from the solution containing Al, Fe, Mn and Ni, using Na₂CO₃, (NH₂)₂CO and (NH₄)₂S₂0₈ as the precipitant are demonstrated.
The results obtained are as follows:(1) The addition of oxidizing agent (NH₄) ₂S₂O₈ to the solution is effective for the separation of Mn.
(2) Al precipitates from the homogeneous solution containing (NH₂)₂CO.
(3) Decreasing the velocity of Na₂CO₃ addition is effective for the separation of Al from Al and Ni in the solution containing (NH₂)₂CO.
(4) Jarosite process can be applied to separate Fe from the acid solution containing Fe and Ni.
(5) Ni can be recovered as quickly settling precipitate from the homogeneous solution containing (NH₂) ₂CO.

抄録全体を表示

The rate controlling step was examined for the reduction of zinc oxide in a coked briquette which was prepared from zinc calcine and coking coal by utilizing the latter as both a binder and a reducing agent. It has been found that the obtained data are best fitted by assuming the rate-controlling step for the reaction to be the diffusion of gases involved in the reaction through the gas film on the surface of a shrinking zinc oxide particle. From the temperature dependence of the reduction rate of zinc oxide, the apparent activation energy for the diffusion was found to be 35.5 kcal/mol. This apparent activation energy seems abnormally large for a diffusion process of gases through a gas film, and it is considered that the overall reaction might be affected by the carbon solution-loss reaction which gives a rather large activation energy. It is so far impossible, however, to evaluate the change of the surface area of carbon in the briquette in the course of the reaction, for the shape of the carbon is not particulate but a kind of matrix for zinc oxide particles because the briquette was pressed into shape while the coking coal was hot and fluid.

抄録全体を表示