Basic knowledge of open pit mining

I. Introduction to limestone:

Limestone (Limestone), referred to as limestone, is a carbonate rock with calcite as the main component, sometimes containing dolomite, clay minerals and detrital minerals, belongs to, is a kind of diagenesis. Limestone is mainly formed in the shallow sea environment, belongs to the formation of biological sedimentation, its main formation is the settlement and accumulation of Marine organisms, coupled with animal and plant detritus from the land and sediment together in the riverbed or seabed after the formation of geological changes.

Second, the composition of limestone structure:

The composition of limestone is mainly calcite, accompanied by dolomite, magnesite and other carbonate minerals, but also mixed with other minerals, such as magnesite, quartz, stone pulp, opal, aluminum silicate, pyrite, pyrite, goethite, glauconite and so on. In addition, in individual types of limestone, there are coal, asphalt and other organic matter and gypsum, anhydrite and other sulfates, as well as phosphorus and calcium compounds, alkali metal compounds and strontium, barium, manganese, titanium, fluorine and other compounds, but the content is very low. The main chemical composition of limestone is CaCO3, which is easy to dissolve, so stone forests and karst caves are formed in limestone areas, which is called karst topography.

The structure of limestone is relatively complex, there are two kinds of clastic structure and grain structure, in which the clastic structure is mostly composed of particles, micrite matrix and sparry cement, and the grain structure is the crystal particles precipitated by chemical and biochemical processes.

Iii. Classification of limestone:

According to its deposition area, limestone is divided into Marine sedimentary rocks and continental sedimentary rocks, with Marine sedimentary rocks being the most.

According to its formation type, limestone can be divided into three types: biological sedimentary, chemical sedimentary and secondary.

According to the different components contained in the ore, limestone can be divided into three kinds of siliceous limestone, clayey limestone and dolomitic limestone.

According to the structure, limestone can be divided into bamboo foliate limestone, shape limestone, mass limestone and so on

Four, the characteristics of limestone:

1. Limestone is widely distributed, the lithology is uniform, easy to mining and processing, is a very widely used building stone.

2. Limestone has good processability, gas permeability, sound insulation and good cementation properties, can be deeply processed applications, is an excellent building decoration material.

3. Limestone is widely produced, the color texture is quite abundant, there are gray, gray, gray black, yellow, light red, brown red and other colors, there are good decorative.

4. The texture of limestone is fine, the processing adaptability is high, the hardness is not high, and the carving performance is good. It is easy to make small shelf carving, which is suitable for beginners to choose, but because the limestone is easy to dissolve, it is not suitable for outdoor carving.

5. Limestone is widely used in metallurgy, building materials, chemical industry, light industry, construction, agriculture and other special industrial sectors are important industrial raw materials.

Basic concept and description of open pit mining

Open-pit mining is the mining of ore in an open space within a certain range, stripping away the topsoil covering the upper part of the ore body and the surrounding part of the rock. So in order to extract the ore, the ore must also be mined.

I. Basic statement:

1. Step (bank) : (Figure 1-1) When mining, the ore and rock are divided into horizontal layers with a certain thickness from top to bottom, and the mining is carried out by independent mining and transportation equipment. Each layer maintains a certain advance relationship, thus forming a ladder shape.

The steps are composed of the following elements: upper flat plate, lower flat plate, slope surface, slope top line, slope bottom line, height, slope Angle.

Steps:

Work step - work flat layout of mining and transportation equipment.

Non-working step - security platform: used to cushion and intercept sliding rocks and slow down slope angles.

Sweeping platform - Stop sliding rocks and clean them with sweeping equipment.

Transport platform - as a link between the work step and the access ditch transport.

(2) Working line (Avdvance line) : a section of mineral rock that has been prepared to form.

3. excavation zone: During mining, the steps are divided into several strips, which are mined successively, and each strip is called excavation zone.

2. Electric shovel... Depends on shovel digging and unloading radius.

4, Each strip mining can also be divided into several sections with independent mining equipment.

Parameter: Length... The length of a working line occupied by an electric shovel.

5. Open pit:

Divided by use:

① Access ditch... Establish transportation channels between mining levels. (AB in BL-4).

② Open a ditch... Establish the first work line (initial step) as shown in CD in Figure L-4.

Divided by section shape: whole section (1-5 a), unilateral groove (1-5 b)

6. open pit An area where open pit mining has taken place and is taking place, formed by steps and open pits.

Hillside open air: closed circle above. Sunken open air: closed circle below.

Constituent elements:

(1) Side wall: the overall surface around the open-pit mine, divided into: top wall, bottom wall (slope), end wall.

(2) working slope (working slope of respose).

(3) working slope and working slope Angle.

(4) Non-working slope surface and final slope Angle.

(5) Upper and lower final boundary line...... A closed curve where the surface of a non-working slope intersects the surface or the floor of an open pit at the end of mining.

(6) Final limit of open pit: the position defined by the final limit line at the upper and lower end.

Second, open pit mining process:

Perforation - blasting - mining - transport - discharge.

Process form: discontinuous process, continuous process, semi-continuous process.

These production links are closely coordinated with each other, so while constantly improving each production link, it is necessary to examine their links in order to improve the comprehensive production capacity of the all-open pit mine.

Third, the development process of open-pit mine project:

As mentioned earlier, the extraction of ore and rock from open pit mines is achieved from a certain process, and this work is generally referred to as open pit engineering.

Open pit mine engineering: according to the construction object, stripping engineering and mining engineering; According to the construction form, it can be divided into digging ditch works and covering works.

The development of mine engineering is carried out according to certain procedures.

For a step: Dig in and out of the trench opening section of the trench expansion.

For the upper and lower levels: trench digging and flank expansion are carried out at the same time, that is, the upper horizontal flank expansion is carried out at the same time as the lower horizontal trench digging, so:

The mine engineering depth continues to increase until the final mining depth.

The line of work at each level of production continues to advance outwards from the position of the initial ditch until the final boundary.

In the process of development, the open-pit mine gradually changes from small to large, from shallow to deep, and continuously extracts ore and strips rock until it is mined within the final boundary. The essential feature of the development process of open-pit mine engineering is gradual, that is, the mining work should continue to move in space, the step work line should continue to expand and advance, and the open-pit will expand further and further.

The characteristics of open-pit mining work are summarized: the production object is the natural ore rock, the mining site and production conditions continue to change, the old level continues to end the new level of production, forming the mining process from preparation to production and from production to new preparation of the cycle of movement law, so that digging, stripping, and mining between the three always maintain interdependence and mutual constraints.

Open pit mining plan

I. The significance of mining:

➤ It is a necessary means to ensure the continuous balanced production of mines

People need to have a plan in mind to do any job. From construction to mining, it usually takes more than a decade or decades, which requires a comprehensive plan, especially the characteristics of open-pit mine production: Production objects and working conditions often change (mine quantity, grade, occurrence conditions, surrounding rock characteristics, groundwater, climate, etc.) The work place is scattered and often moves, there are many production links, and the mining work needs its own preparation, with a cyclic movement law from preparation to production and from production to new preparation. Therefore, it is more necessary to develop a thorough excavation plan. Based on the comprehensive consideration of the cooperation of each process link in the open pit, the development of mining engineering in each period of the mine is made a comprehensive arrangement. In order to make more rational use of manpower, materials and equipment, balanced completion and over-completion of production tasks.

➤ It is an important link to implement the "sixteen character policy" and do a good job in mine management

Mining plan is the use of drawings and tables, indicating the specific time, space and quantity relationship of open-pit mine project development. The open-pit mining policy can be carried out concretely by drawing up plans. Therefore, it is an important document to design and guide the balanced production and comprehensive balance of open pit mine, and an important link to ensure the normal and sustainable production of mine and do a good job in mine management, and must be carefully prepared and implemented.

Division of extractive plans and tasks of each type of plan:

Extractive plans can be divided into two types:

➤ An annual open-pit mining schedule in design

It is an important document of mine design, is the embodiment of design decisions, its task is to determine the initial mine production capacity, balanced production stripping ratio to verify, and arrange the implementation and more accurately determine the open pit infrastructure time, infrastructure engineering amount, time to put into production, production deadline, design calculation year and the total amount of mining and stripping. Advance the position of the work line year by year, and calculate the equipment, personnel and materials required for each period and other mine facilities according to this plan.

➤ Annual, quarterly and monthly mining plans prepared by producing mines

It is one of the contents of the annual production plan of the production mine, but also the core of the annual production plan, is an important document for the organization and management of mine production. Its task is based on the output, quality, technical quota and other indicators issued by the state in the year. According to the requirements of the mining schedule in the technical design, the mining work of the year is arranged. Therefore, in addition to arranging the position of the work line at the end of the year or the end of the season, it is also necessary to calculate the production capacity of the main production processes and auxiliary workshops such as vegetable explosion, mining, transportation, soil discharge and machine repair in detail, identify the weak links, and formulate corresponding measures to ensure the completion of the production task.

Iii. Basic contents and preparation requirements of the mining schedule plan:

Construction content

The mining schedule of open pit mine is usually expressed in the form of chart, which reflects the relationship between the time, scenting and mining and stripping amount of mine engineering development. In other words, the development state of mine engineering is expressed from these three aspects.

Time: the start and end time of open-pit construction, the time of putting into production, the time of reaching the new level of production.

Space: the spatial position of each project, the advance relationship of each level of advancement, the relationship between expansion and extension.

Quantity: the amount of infrastructure works, the amount of ore mined year by year, the amount of stripping, the amount of digging ditch, the ratio of production stripping and mining, the schedule of mining.

The schedule should be prepared year by year, generally prepared to 3-5 years after the design calculation, the so-called design calculation year is the year when the ore has reached the specified production capacity and started production with the equilibrium production stripping ratio, and the total amount of mining and stripping begins to reach the maximum. The total amount of mining and stripping is the basis for the calculation of mining equipment, power, material consumption, staffing and building scale.

1. Mining level stratification plane

It should be prepared on the basis of the geological stratification plan, the amount of ore and rock mined year by year, the number and platform number of working excavators, the position of access ditch and opening ditch, the boundary line of ore and rock, the mining boundary and the position of the working line at the end of the year, etc. This indicates the state of project development year by year on a certain step.

2. Mining comprehensive plane at the end of the year

It is prepared on the basis of excavation horizontal stratification plan. It has the position of the working line of each level, the position of the access ditch and the opening ditch, the configuration of the excavator, the dividing line of the mine and rock, the mining boundary and the line setting of the transport station. This indicates the development status of mine engineering at the end of a certain year, including the length of working line, the width of working flat plate, the excavation of inclined ditch and section ditch, the advance relationship between upper and lower levels, the reserve ore quantity, the working face line and the excavator configuration.

3. Annual production development chart

On the basis of the completion of the mining schedule, the mining plan is only prepared 3-5 years after the design calculation, and the future output can be roughly determined in 3 or 5 years.

Establishment requirement

1, as soon as possible to meet the national requirements for ore production, according to the specific situation of the open pit mine, should be as much as possible to reduce the amount of infrastructure projects, accelerate capital construction, to ensure that within the specified time to put into production, put into production as soon as possible to achieve the design production capacity.

2, maintain the specified reserve indicators at all levels to ensure the balance of production, in the mining of a variety of grades of ore, but also require a variety of industrial grades of ore production and quality to maintain stable and regular changes.

3, correctly deal with the contradiction between stripping and mining, implement the policy of "mining and mining in parallel", the production stripping ratio should be arranged economically and reasonably, the maximum production stripping ratio period should not be too short, and the stripping ratio of two different periods should not change too much.

4, the upper and lower level of the working line to maintain a certain advance distance. Make the width of the flat plate less than the minimum working width of the flat plate, the working line should have a certain length, and keep as regular as possible. To ensure the minimum curvature radius of the line and the transportation road at all levels, the mobilization of mining equipment should not be too frequent.

5. The horizontal promotion and deepening of the steps should be closely coordinated. It is necessary to open up the new level in time to ensure the connection of mining and ore reserves, and in the process of expansion, it is necessary to comply with the predetermined mine engineering development procedures.

6. For phased mining mines, the relationship between staging and transition should be handled well, and the connection of transitional projects and the stability of output should be ensured.

Mining design requirements and preventive measures

1. Basic Principles and guiding ideology of design:

(1) Implement the guiding ideology of "people-oriented";

(2) Implement the safety production policy of "safety first, prevention first";

(3) The selection of low energy consumption, high efficiency, safe and reliable, easy to operate and maintain equipment;

(4) Select reasonable mining technology and development transportation plan, and strive to be technically reliable and economically reasonable, so as to avoid harm caused by environmental factors while developing and utilizing mineral resources.

Second, the main content of the design includes the production system and the auxiliary system, which is mainly divided into the following three parts:

(1) Mining:

Determination of open pit mining limits;

Determination of development mode and mining method;

Selection of production process;

Approval and selection of production equipment capacity (excluding ore processing and external transportation equipment and facilities).

(2) Auxiliary system:

Mining area general map transportation;

Mine power supply, machine repair, water supply and drainage, heating;

Construction of mines, production and living facilities;

Safety and industrial hygiene;

Environmental protection in mining area.

(3) Estimates of investment and enterprise economic benefits.

According to the existing data and the current situation of mining, after consultation with the owner, this design only makes a complete design of mining engineering, and only makes a preliminary estimate of auxiliary facilities (mechanical repair, auto repair, electrical repair, water supply, power supply, external transportation and communication of stope) and living welfare facilities. The owner carries out relevant technical transformation according to the comparison design of original facilities to meet the design requirements. In this design, only the budget estimate is included in the total investment for financial evaluation and economic analysis.

Iii. Preventive measures in design:

➤ Goaf treatment method

For limestone mines, after the closure of the pit, planting trees or refarming after soil covering.

➤ Measures to ensure the final slope stability and prevent slope collapse in open pit mines

(1) Mining shall be carried out in accordance with the relevant design parameters, and the safety platform shall be set up in time.

(2) For the blasting near the final boundary, controlled blasting is adopted to maintain the integrity of the rock mass and the stability of the boundary.