Introduction to Recent Results of Geologic Activities at the Shimokawa Deposit

概要

論文の詳細を見る
(I) Result of prospecting at the Shimokawa deposit. When the Mitsubishi Metal Mining Co. Ltd. acquired the Shimokawa Mine in Hokkaido during 1941, there was no reliable data except a single "Panke" outcrop, and no one was able to anticipate development of the present large scale deposit. During the early period of development, the northern part of the deposit was prospected successfully from north to south for about 500m long. But where the ore body pinched out, it was difficult to trace a southern elongation of the deposit by surface surveying, because the surface is covered by thick post-mineralization Tertiary volcanic rocks. Since initiation of a geological department at the mine during 1951, a systematic detailed geological survey, which has included reconnaissance, electrical and chemical prospecting, and boring, has been emphasized. As a result the contact zone between diabase (the foot wall) and pre-Cretaceous slate (the hanging wall), in which the ore body was expected, gradually became definite and the presence of the ore body was confirmed by boring and drifting. At present a deposit of the following size is confirmed. a. Dimensions of the known ore deposit: vertical-270m., horizontal-1, 500m., mean width-5m. b. Expected elongation of the deposit: 12km. c. Amount of ore reserve found during the past 5 years: 1, 330, 000t. d. Amount of present ore reserve after JIS: 2, 020, 000t, Cu 2.52% S 29% (II) Improvement of boring operations using a newly designed sludge sampler and electric logging. Up to recent core boring has been used for prospecting, however, core recovery was generally so low that results were not always satisfactory. Further, this method is rather expensive. Because non-core boring has higher drilling efficiency, we were able to change from core-boring to non-core boring, without loss of accuracy, by using a newly designed sludge sampler and electric logging in bore holes. Results obtained are as follows: (a) Drilling costs per meter were reduced 25% (b) The grade of the ore and the nature of the ore body and the country rock were determined as accurately as in the case of core boring. (c) By electric logging of the bore hole, width and nature of vein or rock were determined exactly. (III) Method of determination of the daily crude ore grade. The grade.of the ore is so variable at each face that effective flotation operations are especially difficult. To overcome this difficulty, the daily grade of crude ore is determined by the following methods: Grade of excavated ore at each face is calculated by daily sampling. From the tonnage and grade of the ore excavated at each face, the average value at the mouth of the main transporting tunnel is calculated. The calculations agreed well with that determined later at the dressing plant, within the limit of ±0.1% Cu. Excavated ores at the face are transported to the dressing plant one or two days later, so the dressing engineer knows the grade of feed ore prior to treatment and can arrange proper dressing conditions. This method made possible planned mining and dressing operations; the grade of concentrate and percentage extraction by flotation have been improved remarkably.
資源地質学会の論文

Introduction to Recent Results of Geologic Activities at the Shimokawa Deposit

スポンサーリンク

概要

資源地質学会 | 論文

スポンサーリンク