- Average air temperature: 23.1 o C
- Average temperature of the hottest month: 28.6 o C (July)
- Average temperature of the coldest month: 16.6 o C (January)
- Temperature fluctuation range in hot season: 13 o C - 23.1 o C [15]
Rainfall
* Rainfall: Rainy season from May to October, dry season from November to April of the following year. On average, there are about 31 rainy days a year, with average annual rainfall of over 2000mm.
The highest monthly rainfall was 1,126.1 mm recorded in August 1995. This is also the month with the highest daily rainfall (250 mm). The highest annual rainfall was 2,915.4 mm (1973). [15]
Humidity
The average annual relative humidity of the air in the area is approximately 82.8%. The characteristics of relative humidity in the two seasons are as follows:
- Average relative humidity of the highest month (March): 89%
- Average relative humidity in the lowest month (November, December): 77.6%
- Highest average relative humidity (March): 97.2%
- Lowest average relative humidity (December): 59.4% [15]
Wind
In the study area, there are four main prevailing wind directions during the year: North, Northeast, South and Northwest.
- From November to March, the prevailing wind direction is: North and Northeast.
- From April to August, the prevailing wind direction is South.
- From September to October is the transition period between wind directions.
- North wind accounts for 27.2%, Northeast wind accounts for 47%.
- South wind accounts for 14.2%, Northwest wind accounts for 12.3%.
- Calm wind accounts for 9.3%.
- Wind at level 1 ÷ 3 m/s accounts for 49.2%.
- Wind from 15m/s and above is insignificant. [15]
Unusual weather phenomena
* Storms: Quang Ninh is a locality that often has storms, the time of storms usually appears from June to October, the main wind direction is South and Southeast, the storm is often accompanied by heavy rain.
- Wind speed in storms is mainly <= 25 m/s.
- The maximum wind speed in a storm is 30 ÷ 40m/s.
* Fog and visibility: In the study area:
- Number of foggy days in a year: 26.1 days, of which March is the month with the most fog: 6.9 days.
- The month with the least number of foggy days is June: 0.3 days.
- The year with the most foggy days was: 45 days (1972).
- The year with the least number of foggy days is: 11 days (1983).
The number of days with visibility < 1 km is 20.6 days/year, concentrated in the winter months, the most in March at 5.3 days, the least in July at 0.1 day. [15]
3.1.2 Socio-economic conditions
The Nga Hai coal mine of Quang Hanh Coal Company Limited - Vinacomin is located in an area with many active mines and coal mining sites (East borders Khe Tam mine; South borders Tay Khe Sim mine; West borders Tay Nga Hai mine). Infrastructure system: The traffic road from the mine connecting to National Highway 18A and Duong Huy area has been completely concreted, very convenient for transportation, the electricity and water supply system is quite convenient and complete.
Nga Hai coal mine area is located in Duong Huy commune, Cam Pha city with the natural land area of the whole commune being 4,661.8 hectares, accounting for 9.58% of the natural land area of the whole city. [15]
a) Economic conditions:
- Agriculture: Agricultural land area is 120 hectares with an average yield of 165 kg/sao, average food per capita is 365 kg/person/year. The herd of buffaloes and cows is 1,015, the herd of pigs is 1,850, poultry is 6,557, the average annual growth is 5-7%.
- Forestry: In recent years, the people of Duong Huy commune have actively participated in forest protection, afforestation and reforestation of bare hills. In the past 5 years, the whole commune has developed 102 more households with forest gardens with an area of over 500 hectares of various trees.
- Industry: In the commune, there are many units participating in coal mining activities such as Ha Rang Coal Enterprise, Duong Huy Coal Company, Khe Tam Coal Factory, Coal Factory 86, Coal Factory 148, Coal Factory 135...
- Traffic: The commune has provincial road 326 running through it with a length of about 8km. In addition, most of the roads have been concreted or paved with crushed stone, only a few roads are dirt roads.
- Commercial services: Along with the economic development of the whole country. Commercial services in the region have been developing rapidly, diversifying in types. Goods serving the people are rich in both quantity and quality. [15]
b) Cultural and social conditions:
- Population: Duong Huy commune is a commune with many ethnic groups living with many different customs and practices. Of which, the number of households living with ethnic minorities accounts for 34% of the total 674 households in the whole commune. The population is unevenly distributed, with a sparse density of about 63 people/km 2 . Duong Huy has 6 ethnic groups: Kinh, San Diu, Tay, Dao, Hoa and Cao Lan. As of June 2005, the whole commune has 674 households, 2,971 people, of which 1,178 are of working age.
- Education: In the commune there is 1 secondary school with 32 teachers, 438 students divided into 19 classes. 01 primary school with 16 teachers, 137 students divided into 10 classes. 01 kindergarten class with 2 teachers and 46 children.
- Health: Duong Huy commune has 01 medical station with 5 medical staff, health care work is always maintained regularly by the commune, expanded vaccination for children of all ages in the area reaches 98-100%, every year there are 260-320 people coming to the clinic for examination and treatment.
- Historical culture: Within the project implementation area, there are no cultural or historical works, however, near the project there is a small communal temple.
The majority of the people in the area are long-time settlers. A large part work in coal mines and other industrial production facilities, the rest live on small-scale business services and forestry production.
Energy: The national power grid has been extended to every hamlet to serve production and daily life of local residents. [15]
3.2 Current status of mining and dumping at Nga Hai mine seams of Quang Hanh Coal One Member Co., Ltd. - Vinacomin
3.2.1 General overview of the mineral exploitation area
- Geological structure of the mine: [6]
a. Stratigraphy
Is the area on the northwestern edge of the Cam Pha block belonging to the Hon Gai moat.
The mine strata contain up to 35 coal seams, the coal seams have thicknesses ranging from very thin, thin to medium. Seams: 3, 4, 4B, 5, 5A, 6, 6A, 6B, 7, 7A, 8, 9, 10,
11, 12, 13, 14, 15, 16, 17, 17A, 18, 19 belong to thin to medium thickness layers.
Veins: 1, 1A, 1B, 2, 2A, 3A, 3B, 3C, 4A, 4C, 5B, 5C exist in the form of very thin veins. Coal veins have structures ranging from simple to complex and extremely complex.
b. Construction
Within the mine area there are many faults and folds.
*Wrap
In Nga Hai mine area, there are 2 anticlines and 3 main depressions. All are incomplete folds.
- Northern block anticline: Distributed in the Northeast of the mining area. Southeast axis
- Northwest. The axis is slightly inclined to the north (80 o ), the two wings of the anticline are slightly sloping and asymmetrical, the angle of the north wing is from 15 o 20 o , the angle of the south wing is from 25 o 30 o . The anticline axis is discontinuous, cut and displaced by the faults FH, FM, F.4, the axis length is about 2000 2500m.
- Central anticline: This is a large anticline, distributed along the Central block. The axis has a Southeast - Northwest direction, the axis surface is slightly inclined to the North, the two wings are not symmetrical, the slope angle of the North wing is from 15 o 20 o , the slope angle of the South wing is from 20 o 25 o . The discontinuous anticline axis is crossed and displaced by the F.3 and F.3 A faults . The axis length is from 3000m 3500m.
- North Block Fold: Distributed in the middle part of the North Block, the axis direction is nearly East-West. The axis surface is slightly inclined to the North (80 o ). The two wings are not symmetrical, the slope angle of the North wing is from 20 o 25 o , the slope angle of the South wing is from 10 o 15 o . The length of the fold axis is from 1000m 1500m, discontinuous, cut diagonally by the F.4 fault and displaced by 100m 150m.
- Northeast fold: Distributed in the North of the mining area, the fold axis has a direction close to West-East. The axis surface is slightly inclined to the North about (80 o ). The two wings are not symmetrical. The slope angle of the North wing is 18 o 20 o , the slope angle of the South wing is from 35 o 40 o . The discontinuous fold axis is displaced by two cross-cutting faults F.7 and F.8.
- South Block Fold: Distributed along the South of the mine. The axis has an unstable West - East direction, not continuous, being cut diagonally by the F.11 fault, the length of the axis is up to 4000m. The axis surface is slightly inclined to the North (80 o ). The two wings are not symmetrical, the slope angle of the North wing is 40 45 o, the slope angle of the South wing is 30 o 35 o .
In addition to the main anticlines and depressions in the Nga Hai mine area, there are many high-order anticlines and depressions with diverse fold axis directions, creating a very complex mine structure.
*Fault:
The fault development in Nga Hai mine is very complex.
+ According to the level of destruction, it can be divided into:
- Regional faults: including AA and Bac Huy faults.
- Faults with large displacement distances between two wings are F.1, F.2, F.3, F.4, F.5, F.6, F.7, F.8, F.9, F.10, F.11, FH, FM. This type has displacement distance between two wings from 50m 380m.
- Small faults include: F.12, F.14, F.15, F.16. This type has a very small displacement distance of 2 wings from 30m 50m.
+ According to nature, it can be divided into two types:
- Normal faults: including Bac Huy FM, F.5, F.6, F.1, F.8, F.8 A , F.10,
F.15.
- Reverse faults: including F.Đ, F.Đ KT, F.2, F.3, F.3 A , FH, F.4, F.7, F.9, F.11,
F.12, F.14, F.16. These faults have very small damage zone widths.
- Overview of the mine: [6]
a) Current status of existing items and works
The company has quite completely built the construction items on the site including the mine door site +20 South area; Mine door site + 27 seam clusters 15, 16, 17; Explosives warehouse site; Materials warehouse site; Mine Center operating building site. Specifically:
+ Construction site office area +27: 200-seat dining room (2 floors); laundry room; clothing distribution house; battery light house; construction site office house; shift change house; medical house + operator house; 18m long, 7.5m wide bridge over the stream; worker housing; toilets 1, 2; cultural house; library; bakery house; canteen.
+ Coal warehouse floor plan +148: Beam bending house; Electromechanical workshop shift change house; Mechanical repair workshop warehouse; Mechanical repair workshop shift change house; Electric motor repair house; Hydraulic column repair house;
+ Furnace door area + 20 South areas: Shift change house No. 1; Shift change house No. 2; Toilets No. 1, 2; Workers' rest house for shift 2; Guard house; Bunker; Loading crane station; High-lifting station; 900mm rail track platform; Wood sawmill; Fixed air compressor station; Trolley depot; Tram depot.
+ General manager of the company
+ Electricity, water and communication supply systems
+ Road system from National Highway 18A to the mine center
b) Construction preparation works
When the project to maintain and expand the open-pit mining of Nga Hai mine comes into operation, no new construction items will be built but will be used together with the existing construction items listed above and 02 additional small-scale mobile transformer stations will be invested to serve the electricity supply.
c) Current exploitation status
Currently, Quang Hanh Coal Company Limited is mining underground from level -50 ÷ LV and partly open pit with total output 1.3 million tons per year. The life of underground mine from level -50 ÷ LV will end in 2015, so the mine is currently digging tunnels to clear the level below -50 according to the Investment project for underground mining to depth below -50. The project is also mining open pit coal in areas A6 and A9.
d) Mine capacity and life
Coal mining output is 200,000 250,000 tons/year corresponding to the volume of stripped soil of about 2 2.6 million m3 /year.
The open-pit mining life of an open-pit mine is 6 years.
Table 3.2 Coal mining schedule
Year KT
Excavated soil (m 3 ) | Coal (tons) | Coefficient (m 3 /T) | |
Year One | 2 284 934 | 216 962 | 10.53 |
Second year | 986 288 | 97 000 | 10.17 |
Third year | 2 804 588 | 250 000 | 11.22 |
Year Four | 2 264 758 | 200 000 | 11.32 |
Fifth year | 2 321 087 | 200 000 | 11.61 |
Sixth year | 1 208 930 | 102 562 | 11.79 |
Add | 11 870 585 | 1 066 524 | 11.13 |
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e) Borders and exploitable reserves
Choosing the open pit mining option: Open pit mining outside the influence of underground works operating below or with little influence
First, less coal can be mined but it ensures safety for underground mining.
+ Open pit mining mobilized reserves: 847,633 tons.
+ Industrial coal reserves: 1,066,524 tons.
Industrial coal reserves (raw) are determined based on geological coal reserves minus coal losses during mining and transportation and plus dirt and rock mixed into the coal during mining.
Coal loss and the degree of soil and rock contamination in coal during mining depend on the production conditions and structure of the coal seam, the equipment and the applied mining technology diagram. Therefore, the industrial coal reserves in open-pit mining are larger than the mobilized geological coal reserves. Specifically, in the Quang Hanh open-pit mining expansion project, the industrial coal reserves are 218,861 tons larger than the mobilized geological coal reserves.