Smell given forth at each stage of spontaneous combustion of coal may be common to the many cases of various coals. Therefore, an early detection of spontaneous combustion may be possible by analysis of smell.
Then, first the following fundamental consideration for this purpose was made:
1) Smell given forth with increasing temperature of coal was common to the many cases of various coals.
2) Analysis of the main components of smell was possible by means of 2 or 3 gaschromatgraphs.
3) Characteristic smell of some organic compounds was expressed by concrete words.
4) Before going into the main study, gases produced with increasing temperature of fly ash and wood used undergroud were analyzed. The obtained results are as follows: i) Fly ash produced CO and CO₂ with increasing temperature, ii) Wood produced CO₂ even at normal temperature and iii) alcohols with increasing temperature.

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In the previous reports of this series, the properties of the longitudinal waves through wire ropes were studied both theoretically and experimentally.
Then Zener viscoelastic model was proposed to explain the dynamic properties of wire ropes.
In order to investigate the applicability of the results of the previous reports, the authors have tried, in this report, to analyse the tensile forec of a weight-suspending wire rope produced when the weight drops and applies an impact to the rope.
As a result, the authors have found a fact that, the greater the weight is, the greater is the impact tensile force induced in the wire rope, but the force is not proportional to the weight.

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Milling at Doyashiki of Hanaoka mine is characterized by being rich in the secondary copper minerals, i. e. bornite, covellite, chalcocite and so on. These secondary copper minerals indicate same flotation characteristics as sphalerite, especially in the heaping-warm pulp flotation circuit which was developed in this mine.
Recently, the copper grade of zinc concentrate increased with the content of these secondary copper minerals and consequently it was forced to develop a new method to separate these copper minerals from zinc concentrate. But the adequate methods could not been found for depressing the activated sphalerite by using the conventional flotation methods.
Then the method of depressing the activated sphalerite has been developed and put into operation. This method involves grinding, heating or weathering of the pulp in the presence of sulphur dioxide.
From these results, it was found that the activated sphalerite could be depressed without using any other reagents such as sodium cyanide or sodium sulphide.

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The collecting action of alkyl sulfate or alkylbenzene sulfonate against pyrite was studied from the view point of the separation of chalcopyrite from pyrite. The results were summarized as follows.
1. Pyrite floated in acidic pulp, even in the case where only frother was used, because pyrite surface was oxidized to hydrophobic elemental sulphur. The pH region where pyrite floated extended towards more alkaline side, as the addition of this type of collectors increased. But, pyrite did not float above pH 8, even by the addition of the appreciable amounts of these collectors
2. The native floatability of chalcopytite was varied by the difference of the method of preparation of mineral samples. Chalcopyrite which was dried in vacuum after wet grinding floated perfectly below pH 12 by using frother alone. While, chalcopyrite after wet grinding did not float above pH 10, but, it floated in pH value of about 12 by the addition of small amounts of this type of collectors.
3. There was no substantial difference in adsorption mechanism of these collectors between pyrite and chalcopyrite. The amounts of adsorption decreased with increasing pH when pH exceeded a certain value below which the adsorption amounts of collectors remained constant. Also, in the case of constant pH value, the amounts of adsorption rapidly increased at critical concentration of collector through the formation of hemimicelles.
4. The floatability of pyrite increased remarkably even in the collector concentration less than that of hemimicelle formation.
From the above results, it was concluded that the role of this type of collector was to enhance the difference in native floatabilities of chalcopyrite and pyrite by collector adsorption, thus making it possible to separate chalcopyrite from pyrite at lower pH value than in xanthate flotation. This will be regarded as one of the characteristics of the flotation in which alkyl sulfate type collector is used.

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Molten blister copper taken in situ from an operating converter was refined under reduced pressures of around 1mmHg with a vacuum lift apparatus (the D-H process) using the melt of 6kg.
Sulphur and oxygen in the blister copper were rapidly removed as SO2 gas when nearly the same concentrations of sulphur and oxygen were initially contained in the melt, and the vacuum lifts of 14 times corresponding to the recirculation of about 2 resulted in the final concentrations of %S=%O=0.02, which were approximately the values in equilibrium with the reduced pressure. Another impurities were simultaneously more or less eliminated: 40% of Pb, 20% of As, and 40% of Sb.
A model for the vacuum lift process has been presented and an average value of 0.26 for the removal of Sand O in one lift was obtained.

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When copper converter slag is used as a raw material for iron smelting, copper in the slag must be removed as much as possible, because copper may bring out the hot-brittleness of steel. It is reported that most copper in the slag is found as sulphide.
In this experiment, the various conditions of chloridized volatilization and roasting methods had been investigated by using copper sulphides, copper oxides and converter slag.Chlorine was obtained by decomposition of CaCl₂·2H₂O.
The summary of those experimental results is shown below.
(1) Copper sulphides were chloridized easily more than copper oxides, expecially CuS was converted by roasting at 900°C and 30 minutes.Copper content of its calcine was less than 0.1% and removing coefficient of copper was over 98%.
(2) When Cu₂S was roasted at 1, 100°C after holding at 600°C (it may be named “the two stages roasting” ), copper was chloridized rapidly during the temperature increase (600-4, 100°C).
(3) On the roasting at 1, 000°C, if 17% of. CaCl₂·2H₂O was added, copper in the slag was removed above 95%, but removing coefficient of zinc was below 80%.
However, on the two stages roasting added 30% of CaCl₂·2H₂O, copper and zinc were both removed above 95%. By this method, CaCl₂·2H₂O was decomposed slowly in comparison with 1, 000°C roasting.
From the results described above, the two stages roasting may be considered as one of the useful methods for removal of copper and zinc in copper converter slag.

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