The mining area is located in the area of Wenhe Guanzhuang, Yingqiu Town, southeast of Changle County. The county and township roads in the area are vertical and horizontal, and the traffic is very convenient.
(2) Geological characteristics of the mining area
Changle Asbestos Mine is located in the northern edge of Shuixingshan Barracks in Yishu fault zone, and occurs in gneissic adamellite deformed by super-unit metamorphism in Neoarchean Aolaishan. The ore-forming parent rock is amphibole. Tremolite is distributed in veins, and the fiber structure can be divided into fine and soft fibers to form asbestos ore bodies. See figure 2-4- 1 for the geological map of the mining area.
The geological conditions in the mining area are simple. The structure is single, the north is covered by Quaternary, and a large area of rock mass is exposed in the south.
Figure 2-4- 1 Geological Map of Changle Asbestos Mining Area
1- four yuan; 2- gneiss adamellite; 3- pegmatite dike; 4- plagioclase amphibolite; 5- amphibolite vein; 6- amphibole diorite; 7— Ore body and serial number; 8— Faults and Quantity
1. Quaternary system
(1) Linyi Formation
It is mainly distributed in the east and north of the mining area, distributed in strips along the water system and located on both sides of the river bed, forming the first terrace of the river. This formation is fluvial alluvial clastic deposit, and its lithology is mainly yellowish brown sandy silt and brown sandy soil, with horizontal bedding and cross bedding, with a thickness of 6 ~ 8m.
(2) Yihe Group
It is mainly distributed in the northern part of the mining area, in a strip shape to the east of Wenhe Guanzhuang, along the riverbed and floodplain. It is a modern river deposit, and its lithology is gravel and unequal grain sand. The gravel is granite and timely, and its thickness is generally less than 5m.
2. Structure
The structure of the mining area is simple, and the structural features are mainly fault structures, including F 1 and F2, which make the ore body dislocate, and F2 has no influence on the continuity of the ore body.
(1)F 1 failure (NNSE)
The fault distribution direction is 105, and the depth in the mining area is about 1500m, which tends to the northeast and shows the right-handed tensile and torsional properties. The fault dislocates the ore body, which makes the ore body discontinuous. The dextral dislocation distance is about 150m.
(2)F2 fault (north-south direction)
Faults are distributed in 365 direction, with the east plate rising and the west plate falling, and the dip angle is unclear. The lithology of the two plates is discontinuous, extending about 400m, and the northern end extends to the reservoir.
3. Magmatic rocks
The exposed area of magmatic rocks in the mining area is large, which is mainly the intrusive rocks of the neo-Archaean Oleshan superunit and the neo-Archaean dike.
(1) Wenhe Guanzhuang diorite
Its original rock is amphibole, which was transformed into amphibole by metamorphism and hydrothermal erosion. Its main minerals are tremolite, hornblende, chlorite and vermiculite. It is the parent rock and host rock of asbestos mine in this area.
(2) The super-element Jiangyu element of the Neoarchean Ole Mountain.
The unit is exposed in a large area in the south of the mining area, and its lithology is gneiss and banded medium-fine adamellite, which is the host rock of asbestos mine. Meat red metamorphic granite structure, banded structure, gneiss structure, massive structure. The rocks are mainly composed of plagioclase (40%), quartz (33%), microcline (22%) and biotite (5%). The accessory minerals are apatite and zircon. The altered mineral is sericite, and its chemical composition is shown in Table 2-4- 1 1.
Table 2-4- 1 1 Petrochemical Composition Table Unit:%
(3) Neoarchean dikes
The dike in this period is pegmatite, which is banded and exposed in the southeast of the mining area, with a small scale. The dike strike is 56, the pulse width is about 5m, and the north is cut by a north-south fault. The rock is a meat-red megacryst structure with massive structure, which is mainly composed of feldspar, quartz and mica. The accessory minerals are mainly zircon, apatite and magnetite. The local dikes can be mined as potash feldspar ore.
4. Metamorphic rocks and metamorphism
(1) metamorphic rocks
Metamorphic rocks related to mineralization mainly include tremolite, amphibole and amphibole.
1) Tremolite: Tremolite in mining area can be further divided into phlogopite tremolite and talc tremolite. A banded phlogopite tremolite is exposed in the northeast of the mining area, with a length of180m and a width of 20m. Rock has fibrous metamorphic structure, metasomatic texture and massive structure. It is mainly composed of tremolite (63%), phlogopite (63%) and talc (10%), with a small amount of chlorite (5%) and magnetite (2%). Tremolite in rocks is often replaced by talc and phlogopite, which is a residual crystal. Talc is the illusion of tremolite When the content of tremolite and phlogopite decreases and the content of talc increases, it is called talc tremolite. Both tremolite protoliths are amphibole rocks, which are the products of metamorphism and the ore-forming parent rocks of asbestos mines.
2) amphibole rock: it is the main surrounding rock of ore body, with semi-authigenic granular structure and massive structure. The rock is mainly composed of amphibole (98%), with a small amount of chlorite, biotite and quartz. The accessory minerals are apatite and zircon. Hornblende is the parent rock of asbestos mine.
3) plagioclase amphibolite
It is mainly found in ore bodies, columnar granular metamorphic structures and gneiss structures. The rocks are mainly composed of amphibole (70%), plagioclase (20%) and quartz (8%). The accessory minerals are apatite, sphene and magnetite.
(2) deterioration
The metamorphism in the mining area is mainly regional metamorphism and hydrothermal alteration.
1) regional metamorphism; It is mainly divided into three stages. The first and second stages are progressive metamorphism, which occurred in the late Neoarchean and Paleoproterozoic. The third stage is characterized by universal retrogression, amphibole, tremolite and chloritization, which is a regional metamorphic event characterized by greenschist facies metamorphism and belongs to Neoproterozoic.
2) Hydrothermal alteration and metamorphism: it is the result of the combined action of magmatic hydrothermal solution and metamorphic hydrothermal solution. Asbestos in mining area is mainly formed by hydrothermal alteration, and the alteration process is amphibole → tremolite → asbestos or amphibole → amphibole → asbestos. The formation of asbestos is closely related to metasomatism of metamorphic hydrothermal solution.
(3) Ore body characteristics and ore characteristics
1. Ore body characteristics
Asbestos ore bodies occur in amphibole tremolite veins. Four asbestos ore veins are found in this area, and two ore bodies are controlled by engineering. Asbestos ore bodies are veined, and their distribution direction is completely consistent with amphibole tremolite veins, which are formed by the alteration of amphibole tremolite rocks.
Ore body I is located on a hill 500 meters southeast of Guanzhuang Village, Wenhe River. The ore body is vein-shaped, with a length of about 8 16m, a width of 6.8~28.0m (average 12.7m) and an inclined depth of 70m. Its strike fluctuates in the range of 35 ~ 56, with an overall strike of 40, which tends to the southeast with an inclination of 75 ~ 85. The ore body tends to expand, contract and reverse dip, and the asbestos at the expansion place has high grade and good quality (Figure 2-4-2).
Figure 2-4-2 Guanzhuang Asbestos Mine, Wenhe, Changle 2? Schematic diagram of line geological profile
1-Quaternary gravelly sandy clay; 2- diopside; 3- gneissic medium-grained adamellite; 4- Asbestos ore body; 5— Location and quantity of drilling sampling; 6— Sampling position and quantity of exploratory trench; 7— Number of holes drilled and hole depth (m)
The vein is staggered by fault F 1 and divided into two sections: northeast and southwest (the southwest section is not controlled by the project).
Ore body Ⅱ is located in the southeast corner of Guanzhuang Village, Wenhe River, with a vein length of 580m (engineering control length of 270m), a width of 3 ~10m and a depth of 60m. The overall strike of the ore body is 35, and the occurrence is125 ∠ 65 ~ 76.
The highest grade of asbestos is 76482.66g/m3, the lowest grade is 370.97g/m3, and the average grade is 15837.33g/m3.
2. Ore characteristics
(1) Ore type
The main ore types are tremolite asbestos (about 65%) and hornblende asbestos (about 35%). Tremolite asbestos is mostly distributed in the center of vein and gradually changes into amphibole asbestos. There is no strict boundary between them. Tremolite asbestos is light gray, and the aggregate is slightly green. The fiber length is about 60%, 2.5 ~ 5.5 mm is 30%, 5.5 ~ 20 mm is 5%, and the fiber diameter is less than 0.7 ~ 2.5 mm. The amphibole asbestos is light blue and grayish blue, the fiber length is 0.5 ~ 20 mm, and the diameter is less than 0.0039 mm. In addition, the ore also contains tremolite, amphibole, chlorite and vermiculite.
Asbestos is usually filled along cracks. According to the relationship between asbestos fiber and dike strike, it can be divided into two types: transverse fiber asbestos (vertical vein wall growth) and longitudinal fiber asbestos (parallel vein wall growth). Changle asbestos is mainly transverse fiber asbestos, and the length of asbestos fiber is limited by the size and width of cracks.
According to the length of asbestos fiber, the ore is divided into four industrial grades. Among them, Grade I (fiber length ≥20mm) is 1.5%, Grade II (fiber length 5.5 ~ 20 mm) is 3.5%, Grade III (fiber length 2.5 ~ 5.5~20mm) is 10%, and Grade IV (fiber length 0.7 ~ 2.5)
(2) Ore structure
Ore has fiber structure, metasomatic texture, directional structure and massive structure. Fiber structure is the most important structure type of asbestos mine, including fiber metamorphic structure, bundle structure and soft structure, among which soft structure is the main structure type of high-quality asbestos.
(4) Genetic types and metallogenic ages.
Asbestos occurs in amphibole diopside veins, and the surrounding rock is Neoarchean adamellite. According to field observation and laboratory experimental data, the genesis of this asbestos mine is related to magmatic hydrothermal solution and metamorphic hydrothermal solution in the process of regional metamorphism, that is, the combined action of hydrothermal solution and metamorphic hydrothermal solution after magmatic period, that is, amphibole vein is altered by heated liquid to form asbestos mine. According to the characteristics of mineral assemblage, the alteration temperature is about 250 ~ 350℃. The process of amphibole hydrothermal alteration to form asbestos ore is as follows:
Study on Development and Utilization of Geology and Mineral Resources in Changle County
Therefore, Changle asbestos deposit belongs to metamorphic hydrothermal-magmatic hydrothermal deposit.
(5) Chemical composition and properties of asbestos
The identification of this asbestos rock mine is mainly tremolite asbestos, followed by hornblende asbestos. Its chemical composition (table 2-4- 12) is mainly composed of SiO 2 and MgO, which is equivalent to diopside. Single mineral electron probe (JXA-733 electron probe analyzer, temperature 23℃, humidity 55%) analysis results show that asbestos is tremolite asbestos and hornblende asbestos (Table 2-4- 13), which is consistent with the rock ore identification results.
Table 2-4- 12 Chemical Composition Analysis Results of Asbestos Ore Unit:%
Note: Tested by the Fourth Institute of Geology and Mineral Exploration of Shandong Province.
Table 2-4- 13 chemical composition analysis of asbestos mineral structural units:%
Note: Tested by Shandong Central Laboratory of Ministry of Geology and Mineral Resources.
Table 2-4- 14 acid and alkali resistance test results of tremolite asbestos
Note: Tested by the Fourth Institute of Geology and Mineral Exploration of Shandong Province.
Tremolite asbestos has strong acid and alkali resistance. After boiling in HCl, H2SO4 and NaOH solutions with the same concentration for 4h, the average loss rates of asbestos are 7. 13%, 1 1.59% and 0.63% respectively (Table 2-4- 14). The results show that asbestos has strong corrosion resistance, low loss and good acid resistance. Under the same conditions, HCl resistance is better than H2SO4 resistance.
(vi) Physical characteristics of asbestos ore
The physical properties of Changle asbestos ore are mainly manifested in heat resistance, tensile strength and insulation.
1. Heat resistance
The heat resistance of asbestos fiber is expressed by the percentage of combustion loss obtained after the asbestos sample is burned at different temperatures for 65438+0h, and the temperature at which the asbestos fiber loses structural water (H2O+) is taken as the heat resistance of asbestos ore. It can be seen from table 2-4- 15 and figure 2-4-3 that there are two obvious abrupt points in the loss on ignition of asbestos ore. The first mutation point is at 100℃, which is caused by the escape of adsorbed water from asbestos ore and tends to be stable at 300 ~ 700℃. The second mutation point is at 700℃, which shows that with the continuous increase of temperature, a large amount of structural water in asbestos fiber began to escape, and the physical properties of asbestos fiber also changed.
Table 2-4- 15 Asbestos Mine Combustion Test Results
Figure 2-4-3 Heat Resistance Curve of Changle Asbestos Mine
2. Tensile strength
The tensile strength of long fiber asbestos (> > 50mm) and short fiber asbestos (2.5 ~ 7.5 mm) are 83.47kg/mm2 and 46kg/mm2, respectively, indicating that the tensile strength of chrysotile asbestos is 347kg/mm2, which may be related to the strength of tremolite asbestos itself.
3. Thermal insulation
The resistivity of the four samples of the asbestos mine is 3.3×103ω cm, 9.1×103ω cm, 5.7×103ω cm and 4.8×103ω cm, respectively. Compared with Jinzhou asbestos mine in Liaoning (4.9×107ω cm ~1.108ω cm) and Sichuan asbestos mine (6.44×108ω cm), the resistivity of Changle asbestos mine is higher than that of other asbestos mines.