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(1) The basic principles and implementation approaches of circular economy
The economy of a traditional industrial society is a one-way linear economy, namely “resources → products → waste†(see Figure 1). Since the 1990s, people have gradually realized that the root cause of the increasingly serious problems of resources and environment lies in the linear economy model of “high mining, low utilization, and high emissionsâ€, and proposes to establish a circular economy model to achieve sustainable development. 
The circular economy is a green economy operation mode according to the natural ecological material circulation mode. It requires resources to achieve the highest efficiency and maximum recycling through the 3R principle (Reduce, Reuse, Reuse, Recycle). , producing the least amount of waste.
(II) Luquan Group's main resources for developing circular economy
Iron ore, which is the basis for the development of resource mines, according to their own circumstances, can produce iron powder, pellets, copper concentrate, cobalt concentrate and so on.
Tailings and tailings are the main solid wastes produced during the production of iron concentrates, mainly stored in tailings ponds. The main mineral components are: Cu, Fe, Co, etc.; the main chemical components are: SiO 2 , Al 2 O 3 , Fe 2 O 3 , CaO, K 2 O, Na 2 O, TiO 2 , SO 2 .
Mine water, mine water is groundwater extracted from mines in iron ore production. Mine water generally contains suspended solids, oil and some soluble inorganic salts. Direct discharge without treatment will cause pollution to surrounding water bodies.
Waste ore, ore mining process will produce a large amount of waste ore, including some green ore, red ore and other weak magnetic ore, through improved beneficiation methods, the use of hand selection, machine selection and other measures can be selected high-grade ore.
Associated resources, in general, iron ore is associated with rare metals such as Cu, Au, S, Co, etc. These associated ore can be selected in depth under the existing technical conditions, and some are due to technical or high cost reasons. Can not be selected, and a large amount remains in the tailings slag.
Second, the comprehensive utilization of wastewater and technical analysis
(1) Source of wastewater
Underground wastewater. Contaminants such as oil, chemicals and explosives used in the mining process are transported through a large amount of downhole wastewater. The water inflow of each deposit is shown in Tables 1-3.
Table 1 Water inrush in Xiaoguanzhuang Mine/m 3 ·d -1
Table 2 Water inflow from Zhangjiatun deposit/m 3 ·d - 1
Table 3 Water inflow from mines in Hong Kong/m 3 ·d - 1
It can be seen from Tables 1-3 that the total amount of water inflow in the three mines of Luneng Group is 12,612 m 3 ·d. In addition to the wet operation of underground mines, these waters are collected at the level of -400 and -500m through flood discharge channels and small pumps. In the water tank.
Mineral wastewater and tailings reservoir water. The tailings water brought by the tailings slurry, the groundwater infiltrated into the tailings pond and the natural precipitation in the surrounding area.
Mineral processing water is one of the key factors affecting the stability and safety of the tailings pond, so it must be properly controlled. The water mentioned here includes two parts: groundwater and surface water.
(2) Wastewater treatment and comprehensive utilization technology
1. Purification and reuse of ore dressing water
Purification of tailings water. The method of purification depends on the composition and quantity of the hazardous substances, the type of water discharged into the system, and the requirements for the quality of the returned water. Commonly used methods are: 1) natural precipitation; 2) physical and chemical purification; 3) chemical purification.
Return to water and reuse. Try to increase the proportion of tailings wastewater recycling to achieve a closed loop. After the addition of 3 # agglomerating agent in the ore dressing wastewater, the available water quality is achieved (Fig. 3, Table 4).
Table 4 Treatment of ore dressing wastewater
2. Comprehensive utilization of underground water
Lu Mining Group brings down the underground water in the lower level to the large water tank of -400. After purification and sedimentation, part of it is used for domestic water of underground workers; part of it uses high pressure pump to pump water to each working point to carry out wet operation and reduce The dust in the working area; some of it is pumped to the pool of Φ53 m in the surface concentrator. Because the downhole water contains a large amount of SO 4 2 - and Ca 2 - , Mg 2 - , and is weakly alkaline, the pH value is about 8.3, which is suitable for the requirements of the beneficiation process water, so the underground water in addition to the underground operation water, the rest All used for beneficiation.
(III) Economic analysis of wastewater recycling
If the wastewater of the underground metal mine is directly discharged, it will not only cause serious environmental pollution, but also waste a lot of water resources, and also pay a large amount of sewage charges, which will bring a heavy economic burden to the enterprise. After the underground water is collected and treated, it can be used in underground operations and beneficiation processes to recycle wastewater, which can avoid environmental pollution, save resources, achieve emission reduction or even non-discharge, and integrate environmental and economic benefits. After comprehensive utilization of the Group's wastewater, zero emissions have been achieved. This alone saves 2.49 million tons of water per year. The annual sewage discharge fee is 1.49 million, the optional recovery rate of ore is increased by 0.28%, and the sales revenue is increased by 2.8 million yuan. .
Third, the comprehensive utilization of solid waste
(1) Comprehensive utilization of waste ore
The Lu Mining Group produces about 320,000 tons of waste ore each year. These waste ore are first selected by artificial hand to produce weaker green ore and red ore and re-enter the beneficiation process.
The green ore and red ore have different colors due to the different ratios of Fe 3 O 4 and Fe 2 O 3 . Although the magnetic properties are weak, the grade is high and has high selectivity and utilization value.
Waste ore is used to build dams, paving roads, and building materials. The waste ore produced by Lu Mining Group contains a large amount of red slate , which is easily weathered and muddy, and geotechnical sand sinking and damming, the dam body is firm and compact, and it is not easy to form dry shoal. , to avoid secondary dust; also save a lot of land used to store waste ore.
(2) Comprehensive utilization of tailings
Regardless of the type of tailings, the main constituent elements are nothing more than O, Si, Ti, Al, Fe, Mn, Mg, Ca, Na, K, P, etc., but they are in different types of tailings, The t content varies greatly and has different crystallization chemical behaviors.
(III) Comprehensive recovery test of tailings
The iron tailings of underground mines contain a large amount of metal elements. Due to the current mineral processing technology , it is impossible to select all the metal elements one by one. Each 1t iron concentrate should be discharged to discharge 2.5~3 t tailings.
Iron Tailings main sample is martite metallic minerals, minor or trace quantities of magnetite, natural copper, chalcocite, limonite, pyrite, chalcopyrite, sphalerite and the like. The gangue minerals are mainly quartz , calcite , chlorite, serpentine, diopside and the like. The metal elements that can be comprehensively recovered in the sample are Fe, Cu, and Co. The principle process of reclaiming and recovering iron from strong tailing-copper-cobalt-floating-mixed-floating concentrate copper-cobalt separation-mixing and floating tailings can be used to obtain three kinds of products of Cu, Co-S and Fe concentrate. The indicators are:
Cu concentrate: the sample contains Cu 0.094%, the yield is 0.32%, the grade is 20.82%, and the recovery rate is 70.87%;
Co-S concentrate: the sample contains Co 0.028%, the yield is 4.41%, the grade is 0.378%, and the recovery rate is 59.51%;
Fe concentrate: The sample contains Fe 14.53%, the yield is 11.72%, the grade is 55.26%, and the recovery rate is 44.57%.
Fourth, the conclusion
The circular economy of underground mines is fully launched with the main line of “wastewater utilization – waste rock utilization – tailings re-electionâ€, eliminating pollution in the production process, using waste as a new resource for comprehensive development and utilization, vigorously promoting clean production, maximizing the Reduce pollutant emissions and protect the natural environment.
Analysis on the development of circular economy in underground mines
First, the metal mining business cycle economic analysis
Figure 1 Traditional economic material flow
Figure 2 Concept of circular economy material flow
Xiaoguanzhuang-400 level
Diorite
Southern marble
Southwest Daliyan
total
prediction
Maximum water inflow
1302
4200
2539
0.00
1966
50.00
17707
4250
Zhang Mine-250 level
Diorite
Marble
total
prediction
Current water inflow
1402
840
952
0.00
2354
840
Gangli Mine - above 300m
Large amount of rock and limestone
Maximum possible water inrush
-100
-200
-300
1179
2596
3747
9614
11165
15663
Figure 3 Polyacrylamide sedimentation curve
project
Suspended matter / mg · L - 1
Precipitation efficiency
(%)
Temperature / °C
pH
Before precipitation
After precipitation
Unmedicated
After administration
24758
21540
9996
33
59.6
99.85
5
6
8.12
8.05