As one of the earliest precious metals developed and utilized
by mankind, the history of gold extraction has run through the
entire process of human civilization. From primitive gold panning
to modern industrial mining, the progress of gold extraction
technology has always been bound to the development of
deposit types. Global gold resources distribution data show that
the current available deposits are mainly divided into vein
deposits (native rock gold), nugget deposits (alluvial gold ore)
and associated gold deposits of three major types, whose
resources accounted for 5%, 70% and 25% respectively. It is worth
noting that 65% of the current gold production from only 5%
of the total resources of the vein deposits, this production and
reserves of the inverted phenomenon reflects the major
breakthroughs in gold mining technology.
Resource accumulation in the era of
alluvial gold mining
In the industrialized mining technology before the maturity of the
deposit (alluvial gold ore) because of its easy to mine characteristics
become the main object of development. This kind of deposit mainly
exists in the riverbed alluvium or ancient river sediments, gold particles
after long-term geological action has been separated from the mother
rock, the formation of natural gold particles visible to the naked eye.
Early gold miners used a simple water flushing method, using the
physical properties of the high density of gold to achieve initial
enrichment.
The heyday of alluvial gold mining spawned a number of notable
gold-producing regions, and the development process was
characterized by significant geographic migration. Miners usually
tracked upstream along the water system to determine the location
of primary veins by observing the morphology of gold grains and
associated minerals. Although this experience-oriented exploration
method has limited efficiency, it has accumulated valuable geological
data for subsequent rock gold mining.
Technological breakthroughs in rock
gold mining
With the gradual depletion of shallow alluvial gold resources, the
focus of mining turned to the development of vein deposits. This
kind of deposit of gold in micro form embedded in quartz veins
or sulfide minerals, the average grade is mostly between 1-10
g / ton, the traditional physical beneficiation method is difficult
to effectively recover. 20 century industrial application of cyanide
leaching technology has completely changed the mining
pattern, so that the economic development of low-grade
rock gold possible.
Modern rock gold mining has formed a set of standardized
processes: the ore after three-stage crushing to reach millimetre
particle size, through the re-election - flotation combined
process for pre-enrichment, the resulting concentrate into
the leaching system. The leaching link generally adopts
dynamic heap leaching or stirring leaching process, the
precious liquid through the activated carbon adsorption
into the electrolysis process after the final purification. The
gold recovery rate under this system can reach 85-95%,
which significantly improves the resource utilization rate.
Reconstruction of the value of associated
gold deposits
Accounting for 25% of the world's gold resources associated gold
deposits in the development of long-term edge, this kind of gold
is mostly endowed with copper, lead and zinc and other polymetallic
deposits, the content is usually between 0.1-1 g / ton. The traditional
smelting process regards it as a by-product to be recovered randomly,
and the comprehensive recovery rate is less than 30%. With the
adjustment of the precious metal price system and the improvement
of environmental protection regulations, the strategic value of
associated gold is being reassessed.
Modern metallurgical enterprises have realized the synergistic extraction
of metals through process optimization: in the copper electrolysis
refining segment, the recovery rate of gold and silver in anode
sludge has been increased to 98%; the lead and zinc smelting
system has added a precious metal capture device to make the
originally discarded fume become a new profit source. This
model of comprehensive utilization of resources not only
enhances economic returns, but also meets the requirements
of circular economy development.
Technological innovation drives industrial
upgrading
Currently, gold mining is facing a double challenge: the sharp
decline of high-grade easy-to-mineralize resources and
environmental protection standards. The industry's response is
reflected in two technological dimensions: micro-scale
metallurgical technology innovation and macro-level innovation
in the evaluation system of mineral deposits. Bioleaching
technology can reduce the lower grade limit of processed ore to
0.3g/t, and microwave roasting pretreatment can increase the
recovery rate of difficult-to-process gold ore by 15 percentage points.
The development strategy of the deposit puts more emphasis on
the whole life cycle management. The 3D geological modeling
technology can accurately predict the extension of the ore body,
and the intelligent sorting equipment realizes the underground
pre-throwing of waste, which reduces the energy consumption
of transportation by 40%. These technological advances not
only extend the service life of old mines, but also enable the
development and utilization of resources that previously
had no economic value.
Exploring Sustainable Development Paths
Under the constraint of the carbon peak goal, the gold industry is
undergoing green transformation. Cyanide substitution process
has made a milestone breakthrough, and environmentally friendly
leaching agents such as thiourea and thiosulfate have been put
on industrialized trial. In terms of water resource management,
the closed-circuit recycling system has reduced water consumption
from 5 cubic meters to 0.8 cubic meters per ton of ore. The
technological innovation of mine ecological restoration is
especially prominent, and the microbial reclamation technology
can rebuild the soil ecosystem within 3 years.
Future gold mining will show a diversified pattern: high-grade
rock gold ore is still the pillar of production, intelligent mining
technology continues to reduce costs and increase efficiency;
alluvial gold deposits turn to tailings redevelopment, through
precise sorting recovery of micro-fine grained gold; associated
gold rely on metallurgical technology advances to enhance the
comprehensive recovery rate. This multi-path development model
not only guarantees the supply of resources, but also promotes
the sustainable development of the industry.
In the current annual gold production, there are still about 800
tons from the super gold mines discovered in the 19th century,
which not only highlights the continuity of resource development,
but also warns the urgency of the succession of new resources. In
the dynamic balance between technological innovation and
resource constraints, the gold mining industry is writing a new
chapter of development.