358
T.G. Laperdina et al.
The mining of placer gold resources at benches, along and under the riverbed,
which are located, as a rule, in the valleys of small and medium-sized rivers is
accompanied by irreversible landscape degradation and extreme deterioration of
natural water streams, with transformation of their hydrologic, hydrochemical
and hydrobiological characteristics. Recultivating measures at mined-out sites
do not result in restoration of valuable vegetation species, or quantitative and
qualitative composition of water biota in broken water streams. Traditional
technologies of placer gold mining in Russia (dredges and high-pressure
hydraulic giants) are, as a rule, ecologically dangerous, yielding a great deal of
wastewaters with a high content of suspended clay matter. In extreme situations
(rainfall, floods) emergency discharges of wastewaters from settling tanks are not
uncommon. They result in silting of riverbeds, contamination of bottom
sediments and water phase with the toxic metals that are constituents of goldbearing ores (arsenic, antimony, mercury, lead, zinc, bismuth). This leads to a
decrease in quantity and variety of hydrobiota and deterioration of food chains.
Hydraulic methods of gold mining are either forbidden or under strict ecological
control in highly developed countries. Thus, for example, in California, USA,
hydraulic methods were forbidden as far back as 1884, and in Alaska they are
used, but in accordance with the criteria established by the Federal Environmental Protection Agency and Alaska Department of Environmental Conservation (Yeend 1991; Young 1993). In Russia, despite the growth of the placer gold
part of the total production of gold, the control to implement environmental
protection measures in gold mining sites is, unfortunately, weakened. This is one
of the reasons that placer gold mining activity has moved to remote, hard-toreach areas, where the transport system is not sufficiently developed.
2
Sources of Mercury Contamination of the Environment
Due to Gold Mining in Siberia
Mining of ore and placer gold is, as a rule, accompanied by environmental
mercury contamination of differing intensity. The main sources of mercury
emission to the environment are:
- Elevated mercury levels in the rocks and ores of gold deposits and mercury
release during ore and gravel processing, and also its transition into an active
migratory state in the processes of mercury-bearing rock oxidation at sites
broken by mining.
- Direct use of mercury in the process of gold amalgamation of gold-bearing
raw materials and its technological losses due to the use of technically
imperfect equipment (incomplete mercury vapour condensation in the
process of amalgamated gold burning, incomplete mercury trapping in the
process of technological gas purification during forced ventilation, mercury
losses with technological waters during amalgamation).
T.G. Laperdina et al.
The mining of placer gold resources at benches, along and under the riverbed,
which are located, as a rule, in the valleys of small and medium-sized rivers is
accompanied by irreversible landscape degradation and extreme deterioration of
natural water streams, with transformation of their hydrologic, hydrochemical
and hydrobiological characteristics. Recultivating measures at mined-out sites
do not result in restoration of valuable vegetation species, or quantitative and
qualitative composition of water biota in broken water streams. Traditional
technologies of placer gold mining in Russia (dredges and high-pressure
hydraulic giants) are, as a rule, ecologically dangerous, yielding a great deal of
wastewaters with a high content of suspended clay matter. In extreme situations
(rainfall, floods) emergency discharges of wastewaters from settling tanks are not
uncommon. They result in silting of riverbeds, contamination of bottom
sediments and water phase with the toxic metals that are constituents of goldbearing ores (arsenic, antimony, mercury, lead, zinc, bismuth). This leads to a
decrease in quantity and variety of hydrobiota and deterioration of food chains.
Hydraulic methods of gold mining are either forbidden or under strict ecological
control in highly developed countries. Thus, for example, in California, USA,
hydraulic methods were forbidden as far back as 1884, and in Alaska they are
used, but in accordance with the criteria established by the Federal Environmental Protection Agency and Alaska Department of Environmental Conservation (Yeend 1991; Young 1993). In Russia, despite the growth of the placer gold
part of the total production of gold, the control to implement environmental
protection measures in gold mining sites is, unfortunately, weakened. This is one
of the reasons that placer gold mining activity has moved to remote, hard-toreach areas, where the transport system is not sufficiently developed.
2
Sources of Mercury Contamination of the Environment
Due to Gold Mining in Siberia
Mining of ore and placer gold is, as a rule, accompanied by environmental
mercury contamination of differing intensity. The main sources of mercury
emission to the environment are:
- Elevated mercury levels in the rocks and ores of gold deposits and mercury
release during ore and gravel processing, and also its transition into an active
migratory state in the processes of mercury-bearing rock oxidation at sites
broken by mining.
- Direct use of mercury in the process of gold amalgamation of gold-bearing
raw materials and its technological losses due to the use of technically
imperfect equipment (incomplete mercury vapour condensation in the
process of amalgamated gold burning, incomplete mercury trapping in the
process of technological gas purification during forced ventilation, mercury
losses with technological waters during amalgamation).