The high grade of cobalt characterizes the deposit of the Shimokawa copper mine which is one of the most famous bedded cupriferous pyrite deposits of Japan. Unfortunately, however, the cobalt has not been recovered, because the concentration of cobalt is difficult. In order to show the distribution of cobalt in the ore, the microscopic observation and the electron microprobe analysis have been carried out. The main ore minerals are pyrite, chalcopyrite, monoclinic pyrrhotite, sphalerite, cobalt pentlandite, and cobaltian mackinawite in the descending order of abundance. Among them, pyrite is the most important carrier of cobalt, and cobalt pentlandite is subordinate. The cobalt of the copper concentrate depends upon the small mingled grains (less than 20μm) of cobalt pentlandite which is closely associated with chalcopyrite. On the other hand, the pyrite concentrate owes its cobalt amount to cobalt-rich pyrite. On the basis of the texture of ore and the crystal form of pyrite, the mode of occurrence of pyrite is divided into seven types as shown in Figs. 1 (a)-(g). The R-type pyrite having a rounded form is the richest in cobalt among them, and contains a average cobalt concentration of 0.8 wt.%.These natures of ore suggest that the cobalt of the coppem concentmate may be recovered as a by-pmoduct of the copper smelting, and that the cobalt of the pyrite concentrate may be recovered as a cobalt concentrate consisting of R-type pyrite.

抄録全体を表示

With the rapid progress of the chemical industry and the result of coming energy crisis, there is a tendency to increase in usage of a wide range of energy resources and in the quantities. Most typical liquid fuels are liquefied natural gas (LNG). As a result, many diversified hazards associated with LNG are recognized. LNG will be stored in tanks made of, concrete or in underground spaces. But there are many unknown points about behavior of concrete and rocks at low temperatures. Here, the authors studied mechanical characteristics of cement mortar in range of temperature from room temperature to-180°C.
Main results obtained are as follows:
1) The tensile strength of cement mortar becomes maximum at the temperature of about-150°C and is 2.4 times as large as that at the room temperature.(See Fig. 3)
2) The maximum compressive strength is obtained at abovementioned temperature and is 2.2 times as large as that at the room temperature.
3) The maximum Young' modulus and Poisson' ratio are obtained at the temperature of about-150°C, and are1.4 and 1.5 times larger than those observed at the room temperature respectively.
4) When samples are saturated with water, their maximum tensile and compressive strength are 4.5 times as large as values obtained at the room temperatures. And their Young's moduli become much larger.

抄録全体を表示

A procedure by the finite difference method was developed for estimating the heat from the wet surface of a mine airway into air.
In the previous paper, the results of the computation for the distributions of temperature in rock at the several periods of time from the bigining of ventilation were reported.
In this report, the modified procedure for estimating the variations of temperature and humidity of air current was proposed by noting that these quantities were more affected by the wet part of the mine airway than the dry part.
After the comparison of the results by the above procedure with the results of in-situ measurements, this procedure was proved to give the estimation with a sufficient accuracy for the temperature and humidity of the air current passing through the partially wetted mine airway.

抄録全体を表示

In the case of transportation of solids by airlift pump in the deep sea mining and the dredging, it may be considered that the pipelines incline because of the tide and the waves.
The studies on hydraulic transport of solids by airlift pump are very few, and then the studies for investigating the influence of pipe inclination on transportation of solids by airlift pump are overlooked.
The purpose of this paper is to find the influence of pipe inclination on the characteristics of airlift pump at the transportation of solids, and as the basic research for that study, authors investigated the relation between holdup of water in pipe and an angle of inclination (θ) at two and three phase flow by airlift pump.
Main results obtained are summarized as follows:
1.In the case of two phase flow by airlift pump;a._??_θ: radian
2. In the case of three phase flow by airlift pump;d._??_
Where _??_ f_L, f_G=volume fraction of water andair in pipe,
Q_g0, Ql, Q_s=vorume flow rate of air, water and solids,
V_g0=apparent velocity of air at atmospheric pressure,
V_b=velocity of air in pipe, X=friction loss parameter, Δp_f=friction loss.

抄録全体を表示

In the hydrometallurgical treatment of the zinc leach residue, arsenic in the zinc concentrate is condensed into iron precipitate such as hematite and goethite.
So it is difficult to utilize such iron precipitate as raw material for iron and/or its compounds.
From this point of view, the removal of arsenic from the leach solution prior to iron removalstage has been investigated means of corecipitation - with ferric hydroxide which is formed by oxidizing a part of Fe²⁺ion in the solution. The oxidation of Fe²⁺ ion was carried out by aeration under the coexistence of suitable amounts of calcium carbonate, using Denver type flotator.
Sample solution contained 69.8mg/l of As (III), 31.6g/1 of Fe²⁺, 60.7g/l of Zn²⁺and 162mg/l of Cd²⁺.The pH and temperature of the solution were 4.5 and 80°C, respectively.
The concentration of As (III) in the filtrate was reduced to 14 to 10mg/l by aeration for 10 min under the coexistence 2.5 to 5g/l of calcium carbonate and by filtration with No.5C paper filter. But, in this case the filtration rate was very and the filtrate was turbid. When filtration was repeated, the concentration of As (III) in the filtrate was reduced to to 1.2mg/l and the filtrate was transparent. The turbidity of the filtrate was remarkably reduced by using a polymeric flocculant, but the filtration rate was unchanged.When the solution was aerated for 10 min under the coexistence of a small amount of calcium carbonate (1g/l) and agitated for 10 min without aeration after adding 2 to 3g/l of calcium carbonate, the filtration characteristics were considerably imnroved and the concentration of As (III) in the filtrate was reduced to 6.0 to 1.5mg/l. If hernatite is precipitated from this filfrate its arsenic content will be 0.014 to 0.0035%. In this case, the loss of Fe²⁺, Zn²⁺and Cd²⁺was 5.4 to 6.5, 1.6 to 3.1 and 1.3 to 2.3%, respectively and the filtration rate was 2.1 to 2.3m³/m²/hr.

抄録全体を表示

For further understanding on partial chlorination of ilmenite, a thermal gravitation analysis method was applied to chlorination of ferric oxide. A reaction controlling step and activation energy of the iron oxide chloridization were determined from the curves of weight decrease with time under various temperatures and chlorine partial pressures. The reaction mechanisms were also presumed from the relationship between the reaction rates and the partial pressures of chlorine.
In the temperature region higher than 800°C, the reaction is controlled by diffusions of gases of reactant and reaction products, and in the region between 530°C, at which the reaction starts up, and 800°C, by the mixture of the gas diffusion and the chemical reaction.
As the reaction proceeds, the reaction rate is controlled by the chemical reaction.
Experimental equations of the reaction rate are obtained as follows:
Mixed controlling region, _??_
Chemical reaction controlling region, _??_

抄録全体を表示