The article deals with the issue of reclamation of lands disturbed during the development of gold placers. Using the results of surveys and studies of the rocks composing the surface layer, the authors compare the present state of disturbed lands and the technogenic relief designed by technical documents on the development of alluvial placers. The discrepancy between actual and design data is analyzed. The conditions of natural vegetation restoration are studied. Results of observations of the natural vegetation restoration within loose deposits are presented. Recommendations on flattening angles depending on the length of slopes and elevation differences between the bottom and crest of technogenic embankments are given. The design results for reclamation of disturbed lands based on preliminary surveys and mining project data are compared. Methods for reducing the amount of reclamation works are substantiated.
Abstract. The article deals with the structure of gold mining and the prospects of the placer deposits development. The timeliness of the issue on the technogenic placer development has been justified. Their formation causes analysis has been made and the author has been performed the integrated estimation of remaining reserves in-place after the primary deposit development depending on the mining conditions of occurrence and the kind of valued component. The main methods of the enhanced recovery for the placer deposits reworking are offered. General difficulties of the technogenic placer reserves estimation by means of contemporary methods of geological exploration are presented. The author suggested the methods of indirect estimation considering the exploration results of unrecovered deposits and their exploitation during primary placer development. It has been observed that simplification and the speeding up of reserves estimation for technogenic placer makes it possible to enhance its development.
The article describes the dredging method used for developing technogenic placers. Quantitative indicators and qualitative characteristics of rocks were described. Positive and negative experience of placer dredging was analyzed; research results were interpreted. The dredging of technogenic placers using multi-unit dredges was described in terms of specific conditions and parameters. Observation results reflecting changes in dredging parameters, equipment utilization coefficients and uneven operation of dredges were analyzed. Recommendations on dredging efficiency improvement, including the use of controlled dredging, were given. Controlled dredging will help change parameters of chip removed by dippers. Directions of placer dredging involving improvement of existing technical solutions, justification of rational parameters of technological schemes and development of mass conversion technologies were substantiated.
Small limestone quarries are located everywhere. After mining operations have been completed, they are not recultivated and left for self-growing. In order to assess the process of vegetation cover restoration, field studies were conducted at 6 quarries located in different climatic zones of Eastern Siberia and Abkhazia. A description of the quarries was made, and areas of disturbed land were identified. The impact of various factors on the self-growth was studied, including the mining parameters, the size of quarries, the height of ledges, the width of berms, the angles of slopes, the composition of rocks in the surface layer, the exposure of slopes, and the composition of surrounding plants. The research identified factors that have positive and negative effects on the intensity of self-growth; recommendations for forming non-working boards were provided. Mining operations without the implementation of reclamation measures aimed to create favorable conditions for the self-overgrowing of disturbed lands, impair the process of vegetation restoration and entail long-term erosion processes, despite the favorable conditions of the subtropical climate of Abkhazia. The available solutions for land reclamation in Siberian quarries can be implemented in other climatic zones.
The article gives analytical review of the mining and dressing waste situation and the experience gained in the waste exploration and reprocessing in Russia. The authors offer a new procedural approach to the appraisal and calculation of mining and dressing waste accumulations with intent of their re-processing. The approach has been tested under conditions of diamond-containing mining and dressing waste sites.Placer gold reserves decrease yearly in Russia and the world. In the mid-19th century 90% of gold in the world was mined in placers, by the late 19th century, placer-mined gold was under 50%, by the early and late 20th century, it was 15-20 and 10-15%, respectively, and it is a few per cent nowadays. Before 1917 Russia extracted 85% gold from placers, in the 1960s placers gave 60% of Russia's gold, in the 1990s-72%, and in the early 2000s-under 60%. Nevertheless placer gold mining will dominate underground gold mining in the decade to come, and a huge contribution to this is made by gold mine waste accumulations [1][2][3].Placer mining waste with sufficiently high content of useful mineral cover the area of hundreds hectares in Siberia alone. The mining waste accumulate immense gold reserves ranging from several hundred tonnes (in Transbaikalia, Krasnoyarsk, Khabarovsk, Primorski Krai, Amur and Irkutsk gold mining regions [4]) to thousand tonnes (Magadan region). Overall gold amount in mine waste accumulations is estimated as 3.3-5.0 thou t [5] and makes up not less than 18% of total gold reserves in placers [6]. The operating mines can extract gold from mine waste accumulations for 15-70 years according to various estimates [7].Placer mining waste accumulations in Russia are mainly dredge dumps that make up 60-80% in overall share of the placer mining waste [1,2]. In the Khabarovsk Region alone, there are over a thousand of gold-bearing placer mining waste accumulations. The interest in the gold placer mining waste grows with degradation of mine-technical conditions of underground gold occurrences and with severity of ecological requirements.By now there is sufficient experience gained in re-processing of dredge waste. It appears that sometimes economic effect of placer waste re-processing is comparable to the underground mining of higher quality gold reserves. Mining waste re-processing output is sufficiently stable. Re-processing of diamond-containing dredge waste for 7 years produced on average 40-50% of the initially extracted useful mineral. Dredge dump mining in Transbaikalia produced 34-60% of the initially extracted gold [3]. Average gold extraction from dredge dumps in the Lena gold region was 45%.
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