In general, the metal assay value of ball mill or flotator feed are taken as the basis of the crude are grade. Both assay values of the ball mill feed and the flotator feed are theoretically the same, but actually they are not the same.
To investigate this difference in sampling, the writers have studied the influence of are grain size On the assay value. As the lead and zinc has shown the different behaviour in the sampiing test, the writers have considered theliberation degree of the mineral grain as the most important factor in the sampling problem.

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At the present, the complete investigation of Baum Washer is thought to be the most difficult thing, because of including various compliciated elements and difficulty of the measurement.
This paper gives the results of operating condition for Baum Washer as for the under items (1)-(4) and also shows actual examples.
(1) The investigation of operating condition by oscirograph.
(2) The investigation of bed forming.
(3) The judgement of separating results.
(4) The investigation of automatic control.

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After the second War, in Japan; low-ash gas coal has been required by customers under the influence of imported American coal. But it was difficult to produce the low ash coal by ordinary washing processes from high-ash raw coal. Then the problem of cleaner jig rose, which is equipped after the main jig to wash again the cleaned coal.
After our inquiries into results of practial washing operation in jigs, it was found out that the highest jigging, efficiency is gained when the discharge of refuse from each cell is less than 30%.
Since 1954 new cleaner jigs have been successfully operated in washing plants at Shikamachi and Yatake mine successfully. But in operation, it is necessary to use jig beds consisting of feldspars or artificial stones. And it is also desirable to furnish the cleaner jig with the regulators of air pulsation for better operation.

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The coal-preparation plant of Yubari coal mine, Hokkaido, which had been operated mainly with Rheolaveurs for over twenty years, was converted into the Baum-type washer plant in 1954.
The report describes the causes and effects of this conversion, along with the comparison of the Baum-type washer with the former Rheolaveur from technical and economical points of view. Although Baum-type washer is more expensive in the first cost, it produces much more cleaned coal of coking grade because of its sharper separation, resulting in the increase of net profit by about 300 yen per ton of cleaned coal, as well as some savings in operation costs.

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Of the non-ferrous metal mines operated by Nippon.Mining Co., Ltd., Hitachi, Kawayama and Ogoya mines are using 3 different types of separators namely cone, Akins and Wemco drum separators in their mills respectively. The practical data obtained in these mills in th eir sink-float concentration are given here to introduce to readers the actual conditions in these mines.
A comparative study was made to ascertain the causes which affected the separation efficiency. Again, a comparative study was made by obtaining Tromp's distribution curves from the actual result of survey made on samples on the spot and by finding out the sharpness of separation.
Furthermore, from the experiences obtained in using these separators, the characeristics of various separators from the standpoint of operation were given to be used as reference.

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Coal seam in Tagawa colliery, Yamagata Prefecture, is composed of coal, bone coal, coaly shale and shale. So it is very important to beneficiate such poor run-of-mine coal to meet with the demands of consumers.
Five years ago the drum-type sink-and-float separator was installed to treat lump coal, but minus 6mm coal could not be treated with this machine. It was found by several tests that fine coal of 8-1.2mm size was successfully cleaned b, y the “Full Back” type sink-float separator using pyrite cinder as heavy medium material. Details of this process and operating data is given in this paper.

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As Hitachi Mine Mill is depending its supply of water on reclaimed water, a study was made to find- out its effect in flotation. The study showed that the remaining copper cyanide complex ion was the principal factor in bringing about an effective result in copper pyrite differential flotation.
A study was also made to find out the effects of other constituents in copper pyrite differential flotation.As regards the depressing action of copper cyanide complex ion, it was found out on an experimental scale that the desorption of xanthate adhering to pyrite minerals would be caused by this ion, while at the same time, a theoretical study was made on this matter.
Furthermore, a study was made to find out the relation-ship between the nature of water used- and the result of flotation in actual operation. By these means, a standard was established in the nature of water for use in actual operation.

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At Ashibetsu Colliery of Mitsui Mining Co., Hokkaido, six sets of the four-cell doubleoverflow Fahrenwald type flotation machines are being operated to treat fine coal slurry, together with three sets of Oliver filter and a Bird type centrifuge for dewatering of their froth.
The feed slurry enters inte the second cell, and the cells ranging from the second to the fourth of each flotation machine are operated as a rougher, providing the first as a cleaner.
T.F.C. No.1 flotation reagent, made by Takasago Perfumery Co., which is a mixture of camphor oil and petroleum hydrocarbon, has been successfully used for years. The difficulty encountered during winter in coal recovery is remedied by warming the spray water for rougher froth. with a steam heater, and thus keeping the pulp temperature above 5°C.
Although the plant has a froth thickener of 1, 000m³ capacity, it has no ue for the actual dewatering of froth. The Bird centrifuge installed in 1953 has given a satistactory dewatering results comparable to that: of the vacuum filters.

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In the beneficiation of Besshi ores, bulk-differential flotation system had formerly beer adopted. However in October last year a new process, called by us “Bulk-Stage Differential Flotation”, was developed in our mill to better our results.
In this newly contrived method slaked lime and sodium cyanide are added to bulk concentrate before it undergoes regrinding in order to depress the middlling copper and pyrite. And the chalcopyrite isolated by first grinding is first floated and reclaimed by the first-stage flotation process. Then the sink undergoes regrinding in order to have its middling copper liberated, after which chalcopyrite is reclaimed by the secondary flotaiton process.
The resultant grade of the copper concentrate is 20-22% Cu, and that of the pyrite concentrate is 0.21-0.25% Cu. In this way satis factory results by far better than that of the bulk differential flotation method have been achieved.

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The gold ore from Kushikino-mine contains mainly electrum, pyrargyrite and argentite, wheres these minerals are not suitable for ordinary cyanidation process.
We conducted some studies on this ore which was summerized as follows;
1. More effecive cyanidation process.
2. Re-treatment of the cyanide tailing by flotation or gravity-seperation.
3. Flotation followed by cyanidation process.
After all, we had reached to the conclusion that the last process was the most preferable one, and our flotation plant was put into operation in July, 1954.

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Two types of flotation machines are being used as a rougher in the same plant at Ashio Copper Mine; the aged MS Sub-A machine is being replaced step by step with the new Fahrenwald machine. We are going on with a series of tests to investigate the effects of the reconstruction and find out more effective usage of the new machine.
The objects described in this paper are included in those tests. They are
1. Power tests of one cell about the two machines.
2. Testing of the shapes of impellers.
3. Aeration test with a testing machine.
4. Comparative test of the powers of the two machines.
5. Comparison of the staying state of the pulp between the two machines.
As the results of these tests, some characteristics of the two machines have been revealed though the differences of the capabilities between the two left obscure.

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The methods that may be applied to the treatment of slurries and water of coal preparation are related to the problems of coal preparation practice, stream pollution, and loss of coal in preparation. The equipments usually employed for that purpose are cone-type drag tanks and thickeners. A thickener is considered to be a continuous settling pond.
The area required of a drag tank or a thickener is the maximum value from the equation A=V₁/ν
where V1 is the volume of feed water per unit time, ν is the corresponding subsidence rate of minimum of solid of the drag tank or the thickener.
The total volume of the consolidation zone is V=t (V ₀ω₀- V₁ω₁)/ω₂
where V₀ is the feed volume per unit time, ω₀ is weight percent of the feed pulp, V₁ is the overflow volume, ω₁ is the weight percent of solids of the overflow. The consolidation tests show the length of time t that pulp must be held in the consolidation zone in order to produce underfloW of a desired weight percent ω₂.

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Several tests have been made with continuous centrifuges for the purpose of dewatering the flotation froth of fine coal at Sakito (Nagasaki) and Bibai (Hokkaido) collieries, Mitsubishi Coal Mining Co., Ltd.
The results of the tests and performances in actual operations are summarized as follows:
1) The continuous centrifuges tested were proved to be applicable for dewatering fine coal froth.
2) The effectiveness of dewatering and capacity of the machine are greatly affected by the percentage of minus 300-mesh particles in the feed.
3) The ash content of the dewatered coal is about 4 percent lower than that of the feed, owing to the desliming action of the machine.
4) Considering the lives of wearing parts, the speed of rotation and the difference between the speed of outer bowl and inner screw should be preferably low.
5) The dewatering cost is about 170 to 200 yen per ton of dewatered coal.

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The method of tailing disposal at Miyatamata Mine is a so-called “pile up” method. Pulp from the mill plant, 19%solid, -200mesh 50%, flows by gravity in ditches which have been built on the preceding pile up sand terraces, and are paralled with the base dam. Deslimed sand in the ditches is shoveled up into border crests. When the ditches become shallow, the outside of border crest is conditioned in 14°C slope forming dam face.
Advantages of this method are as follows:
1) Low cost of construction of base dam.
2) Easy selection of dam situation.
3) Natural sizing of slime in ditches.
4) Sufficient inspection and good control of dam by laborers.

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The mill of the Oppu Mining Company is located about 30 kilometer west of Hirosaki, Aomori Pref. This mill is built for the treatment of a complex copper-lead-zinc ore, which is transported from the mine by an aerial tramway some 6 kilometer in length. The mill consists of a crushing plant and a grinding-flotation plant, the latter is a modern fireproof building covering an area of 45.5m by 23m and is 16m high. The plant construction was started in May 1953 and was put in operation in Dec. 1953. The capacity is 200tons per day.
The average ore contains about 0.9% Cu, 2.2% Pb, 3.8% Zn, and 10.0% S. The principal metallic minerals in the ore in order of their abundance are pyrite, sphalerite, galena, and chalcopyrite. This mill treats such a complex ore by conventional differential-flotation method, and produces a copper concentrate of 20% Cu, a lead concentrate of 75% Pb, a zinc concentrate of 57% Zn, and a pyrite concentrate of 48% S. The average recoveries are about 84% of the copper, 90% of the lead, 86% of the zinc, and 51% of the total sulphur, respectiVely.

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We had treated only tailings from magnetic separation of iron ore in the copper flotation plant till 1950. Then, according to the development of copper deposits, two plants for copper ores were constructed. One is a small plant which has a capacity of 150 tons per day, and the other is a plant which has a capacity of 600 tons per day.
There are two kinds of copper deposits at the Kamaishi mine.
(1) The 1st. deposit of copper ore:
low grade magnetite ore containing copper ore, average grade: 25% Fe, 0.6% Cu
(2) The 2nd. deposit of copper ore: mixed ores of chalcopyrite, pyrrhotite, and magnetite, average grade: 18% Fe, 1.5% Cu
Ores from the 1st. deposit are treated in 600 tons plant, and ores from the 2nd. are treated in 150 tons plant. In the latter plant, products of ball mill are treated with 750 unit flotation cell, and about 70% of copper contemts are recovered here. And then simks are sent to ball mill of the plant treating tailings of iron magnetic separation plant. In the former plant, copper minerals and iron minerals are recovered step by step by the way of flotation and magnetic separation alternately.

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This paper describes about the lead-, zinc- and manganese flotation at Yakumo dressing plant of Chugai Mining Co., Ltd., which turned in full operation in April 1954.
The deposit of Yakumo mine is the hydrothermal fissure-filling vein which consists of banded vein of sulfide minerals such as pyrite, galena and sphalerite, and of rhodochrosite. Only specific are of commercial value at that time has been selectively mined, rejecting and remaining others unmined.
The differential-flotation plant which has a capacity of 80 tons per day was constructed with the purpose to beneficiate such minerals. Prior to the flotation, ores are washed by washing trommel to remove primary slimes. Large circulating load in combination of a grate mill and a rake classifier prevents over-grinding and harmful effects of secondary slimes on soap flotation of manganese ore, together with desliming cyclone ahead of manganese flotation circuit.
Two combined sulfide froths, one is lead-zinc and the other mainly zinc, are floated in bulk-flotation circuit, and then differentially floated respectively. Manganese froth is floated from bulk-flotation tailing using oleic acid and AERO Promoter 824 in alkaline circuit. Conditioning agents are soda ash, sodium silicate and sodium cyanide. Sticky froth of manganese is destructed by water spray at thickener. Also water spray assists washing out adhered viscous reagents and filterimgofsuchfrothattankers.Warmimgofsupplywaterbymimethermalwaterincold season assists flotation recoveries, especially of manganese.

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It is estimated that about 600 tons of frothers and 1, 200 tons of collectors were used during 1954 in the Japanese flotation plants, treating about 6 million tons of metallic ores per year.
Frothers most commonly used are essential oils such as pine oil or camphor oil, and about 200 tons ofjpine oil is imported annually from the United States. Other frothers such as cresylic acid or higher alcohols are rarely used at present.
Collectors mainly used are xanthates, and most of them is ethyl xanthate. But the consumption of Aerofloats both liquid (mainly Aerofloat *25) or dry (mainly Aerofloat #208) is becoming larger. Collecting oils are still used in some zinc flotation plants.
In the flotation plants of coal, middle oil and creosote oil from coking industry are mostly used as the sole flotation agent.

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