The present paper describes the results of photoelastic experiments conducted for the purpose of determining the relation between the stress around underground levels and the state of initial stresses in the ground. It has been pointed out that the shape of a level as well as the state of initial stresses has a great influence upon the stress on the wall surface of a level. The relation between the stress and the state of initial stresses has been determined for ten kinds of levels.
Considering this result and the: theory of fracture of rock around underground openings, it has been examined what kind of level is preferable from the stand-point of earth pressure.

抄録全体を表示

The authors analysed fracturing characteristics in rocks by the percussion drilling of coal-measures rocks from 21 coal mines in Japan, and they investigated an index that determines the volume of cuttings on the fracturing tests by the pendulum hammer type test machine.
The stress waves are measured by means of wire strain gauge on the midway of long rod when the rocks were struck by standard bit and carried out, the chipping resistance in relation to the waves of incidence and reflection.
On the surface of rock specimens the individual and multiple percussion blows were performed under various conditions. The weight of cuttings is given as follows:W=ηθ/4D{h(kv-F₀)}α where W: weight of cuttings on the multiple blows, θ: angle of rotation, D: diameter of the fracturing hole, ν: velocity of blow, F₀: critical energy of blow, ρ: specific density of rock, h: coefficient of crater depth, η: correct coefficient of the fracturing depth, α: correct index of the fracturing depthk: unit chipping strength
From the above, it was found that the fracturing characteristics in rocks were not experimentally defined without several indexes besides a unit chipping strength.

抄録全体を表示

Train system is usually used in the transport by waggons.But each member of a train does not always be fixed, waggons are transferred from one train to another either in groupe or in solitude.
In this research, it is seeked that the several foundamental laws which govern the disjunction or mingling waggons-bands seperated from trains.The conclusions are following:_??_ Here, x=number of waggons in a same band, t=time that elasped during the transportation cycles, R_i=possibility in percentage that is caculated wheni-linked waggons are derived from a waggons-band, r=commoh ratio ofR_i/R_i-1, (i=1, 2, ..x-1) N_n, _n=number of waggons in the n-th train, N_n, _m=number of waggons in a waggons-band which seperated from n-th or n2-th. train and mixed into m-th or n-th train, ‘a’, ‘b’ ‘k’ and ‘A’ are the constants.

抄録全体を表示

Since World War II, pursuant to the program of rationalization of the copper industry, marked progress has been achieved in mineral flotation methods and conspicuous improvement seen in the production of sulfuric acid thru the utilization of waste smelter gas.
In answer to this developments in mineral dressing methods and with a view to improve efficiency in the production of sulfuric acid utilizing waste smelter gas, the writer having studied the method for converting copper concentrates by direct charge into converters and for devicing means to improve the heat balance in the converter by external charge, has after a series of different tests arrived at the conclusion to utilize oxygen.
(Test, using oxygen in bombs)
As a first step and in order to determine the effectiveness of using oxygen, fourteen basic tests were conducted at the Saganoseki Smelter for one year, commercing May 1951 in conjunction with normal operations of the converters, during which approximately 5, 000 bombs of oxygen were consumed.
(Test, using liquid oxygen)
In the next. stage and with a view to commercialize this process, it was necessary to study operational conditions in detail, for which purpose tests were conducted on a commercial scale, for a period of two years, by installing a liquid oxygen producing unit of capacity 120l/hr and regulating large quantities of oxygen, as desired.
In comparison with conventional blast furnace smelting methods the following merits are to be seen.
(1) The stage of: preparatory treatment of fine concentrates can be eliminated.
(2) Decreased requirements in fuel and fluxes.
(3) Blister copper can be produced direct from the copper concentrates in one single stage operation.
(4) The high SO content in the waste gas is best suited for the production of contact sulfuric acid.
(5) Because'such impurities as lead can be easily removed, the copper content in the anodes is upgraded, which condition is more favorable during electroysis.
In addition Ito these numerous, advantages, the utilization of iron concentrates recovered by dressing the converter slage, combined with the use of low cost oxygen produced in a low pressure air separating plant, it is feasible to
(1) Reduce smelting costs
(2) Improve yields
(3) Recover untapped resources
In other words it was possible to confirm that this new smelting process conforms with the three general principles enumerated above.

抄録全体を表示

Influence of impurities included in copper anode upon the anode potential-time curve has been studied. The anode polarization potential during electrolysis at constant temperature and constant current density was measured against a copper reference electrode. Results for sulfur, lead and oxygen are reported.
Sulfur included in copoer anode formsβ-Cu₂S anode slime during electrolysis. Anode potential is raised and the time to become the passive state is shortened with increase of sulfure content. Lead forms P_bSO₄slime and its effect on anode potential is similar to sulfur. Behavior of oxygen is complicated. At low bath temperature anode potential depends on oxygen content, but at high bath temperature influenced other factors such as current density etc.
Müller's Bedeckungstheorie may be applied at the present investigation.

抄録全体を表示

昭和34年6月15日より, 北海道下川鉱山(三菱金属鉱業), 鴻之舞鉱山(住友金属鉱山), 跡佐登鉱山(跡佐登硫黄鉱業)および釧路炭鉱(太平洋炭鉱)において, 本会選鉱専門委員会の第9回現地研究会が関係各社協力の下に開催された。参加者は山口吉郎委員長以下, 田野孝三(中外鉱), 三野英彦(三井金), 西松和男(日鉱), 米沢利明(日鉱), 若林哲朗(三菱金), 佐々政男(住友鉱), 伏見弘(早大), 今泉常正(東大)の各委員, それに今回は特に客員として高桑健教授(北大)を招き, 合計10名であつた。
以下, 各所における研究会の経過を報告するが,.今回は紙数の都合上, 研究討論会の議事録を主体とし, 各所の選鉱・選炭操業概要については, 系統図を紹介するにとどめた。この点読者の御諒承を得たいと思う。

抄録全体を表示