ENSURING SAFETY AND OPTIMIZING DEMOLITION PROCESSES IN THE MINING OF POTASSIUM LAYERS

ABSTRACT

This article is devoted to modern dismantling technologies used in the potassium extraction process under the conditions of the second potassium layer of the Tyubegatan deposits. In order to increase the efficiency of loading and transporting face equipment in low chambers of potassium deposits, as well as to ensure safety, detailed recommendations are given on the methods of laying and securing dismantling workings. It is emphasized that during the dismantling process, protective sylvinite layers are necessary to increase the stability of the shut-off boundary and the ceiling of the chamber. Also, important technical instructions for ensuring the safety of various types of dismantling work under the influence of mining operations, depending on rock pressure and geological conditions, are presented. Each stage of the dismantling process is explained using specific technological schemes and coefficients, which is essential for the implementation of a modern approach to pota.

АННОТАЦИЯ

Данная статья посвящена современным технологиям демонтажа, используемым в процессе извлечения калия в условиях второго калийного слоя Тюбегатанских месторождений. В целях повышения эффективности погрузки и транспортировки забойного оборудования в низких камерах калийных месторождений, а также обеспечения безопасности, даны подробные рекомендации по методам укладки и крепления демонтажных выработок. Подчеркивается, что в процессе демонтажа необходимы защитные слои сильвинита для повышения устойчивости ограждения и потолка камеры. Также представлены важные технические указания по обеспечению безопасности различных видов демонтажных работ под воздействием горных работ в зависимости от горного давления и геологических условий. Каждый этап процесса демонтажа объясняется с помощью конкретных технологических схем и коэффициентов, что необходимо для внедрения современного подхода к пота.

Keywords: Tyubegatan deposit, dismantling workings, potassium extraction, potassium extraction technology, roof stability, mining conditions, compensation gaps, sylvinite deposits, dismantling safety, dismantling process, anchor fastenings.

Ключевые слова: Тюбегатанское месторождение, демонтажные выработки, добыча калия, технология добычи калия, устойчивость кровли, горнотехнические условия, компенсационные зазоры, сильвинитовые отложения, безопасность демонтажных работ, процесс демонтажа, анкерные крепления.

Introduction. This article discusses the mining processes, dismantling operations, and reinforcement methods used in the second potash layer of the Tyubegatan deposits, which belong to “Dehqonobod Potash Plant” JSC. Potash extraction is a technologically complex process that requires the use of modern equipment and safety measures. One of the main challenges in mining is ensuring the stability of rock masses during excavation and minimizing potential hazards in the pre-face void of the chamber. The article presents recommendations for carrying out dismantling drifts, their reinforcement, and ensuring face safety. These methods are specifically designed in accordance with the geological and technical conditions of the mine and aim to improve production efficiency through the implementation of modern technologies [1].

Additionally, the article provides information on special equipment used in dismantling operations, anchor supports, and other protective measures.

Methodology. This article is based on the development of recommendations for optimizing mining processes and ensuring safety in the second potash layer of the Tyubegatan deposits, owned by “Dehqonobod Potash Plant” JSC. Several key methodological approaches were developed based on dismantling operations, reducing mine pressure, and utilizing advanced technologies. Comprehensive research and practical studies were carried out to ensure the effective implementation of the following methodological processes:

1. Analysis of Geological and Mining-Technical Conditions

The geological characteristics and mining-technical conditions of the mining sites (roof type, sylvinite layers, and mining depth) were studied.

These studies helped determine the optimal parameters for potash mining technology and identify the essential factors for its efficiency.

Special attention was given to the classification of rock types (I, II, III) and the associated mechanisms and methods [2].

2. Development and Analysis of Dismantling Drifts and Applied Methods
The use of modern equipment for loading and transporting dismantling machinery in the chamber faces of the second potash layer was analyzed. Within this process, two main methods for applying dismantling drifts were evaluated:

• Passing the drift in advance, outside the area affected by temporary support pressure;
• Placing the drift near the halted chamber face.

The optimal thickness and placement of protective sylvinite layers for stabilizing dismantling drifts and proper connection mechanisms were also identified and analyzed.

3. Recommendations for Ensuring Chamber Stability

To improve chamber stability, it was recommended to leave a protective sylvinite layer of 0.3–0.4 m in thickness. Based on the defined challenges and the need for continuous chamber stability, support pressure parameters were established and used to develop recommendations [3].

The necessity of designing mechanisms and technological schemes to reduce static loading on the pre-face area and enhance safety during the technological process was emphasized.

4. Selection of Stabilization and Reinforcement Methods for Dismantling Drifts

To ensure the stability and safe execution of dismantling drifts, the use of compensation slots and anchor reinforcement methods was recommended. These reinforcement measures aim to improve the drift's resistance to deformation.
Such reinforcement techniques (e.g., KAMV and KAZ anchors, wooden props) were optimized according to the varying mining conditions and excavation depth.

5. Calculation Methodology and Anchor Reinforcement Technologies
To ensure the stabilization of dismantling drifts, anchor reinforcement technologies were applied along with calculations based on convergence and “roof-to-floor” closure values.
Calculation methods and the use of graphical tools were introduced to assess the stability of dismantling drifts. Based on the computed convergence values, protective and reinforcement measures were selected with greater precision [4].

RESEARCH RESULTS: This study includes recommendations for conducting and reinforcing dismantling drifts aimed at reducing dismantling time and improving safety by utilizing modern equipment for loading and transporting face machinery in low chambers with mining thicknesses of up to 2.1 meters under the conditions of the second potash layer in the Tyubegatan deposits, belonging to “Dehqonobod Potash Plant” JSC. To improve the stability of the roof in the pre-face void of the chamber, it is recommended to leave a protective sylvinite layer with a thickness of 0.3–0.4 meters at a distance of 10–12 meters before the stopping boundary. When dismantling drifts are used and the mining thickness ranges from 1.1 to 2.1 meters, the following specific load values (q) from mine pressure should be adopted for the mechanized supports used in technological schemes:

• For immediate roofs consisting of Type I rocks (based on stability conditions), q ≥ 250 kN/m²;
• For immediate roofs consisting of Type II and III rocks, q ≥ 300 kN/m².

For the connection of the dismantling drift with the roof, a monolithic layer of sylvinite or rock salt with a thickness of at least 0.15 meters is selected.

Depending on geological and mining-technical conditions, two methods for conducting dismantling drifts are applied:

1. Conducting the drift in advance, outside the area affected by temporary support pressure of the dismantled chamber;
2. Conducting the drift near the halted chamber face of the dismantled chamber.

Using the method of conducting the dismantling drift next to the chamber face in the second potash layer is recommended in the following cases:

• If the inter-pillar width in adjacent mined chambers does not exceed 10 meters;
• If the roof consists of non-existent 5th and 6th sylvinite layers.

Dismantling drifts are performed 7–10 days after excavation work, using a transverse section approach. This temporary pause is essential for reducing static load on the face support and the pre-face zone. It enables stress relaxation at the chamber edge, shifts the point of maximum support pressure deeper into the rock mass, and causes complete collapse of the immediate roof rocks.

Conducting dismantling drifts in transverse sections is done in segments of 20–30 meters. During this process, the mining combine is periodically driven backward, and the drift roof is reinforced accordingly with KAMV and KAZ rock bolts. This process is carried out based on the "Reinforcement Passport" developed according to the recommendations.

For dismantling drifts conducted in advance and located outside the impact zone of excavation in the dismantled chamber, protective measures must be chosen. These measures should ensure drift stability:

• Within the temporary support pressure zone from its own chamber,
• Within the residual support pressure zone of adjacent previously worked chambers,
• And during the period when the excavation face intersects the dismantling drift.

The expected "roof-to-floor" convergence (Up) for the final service life of the dismantling drift is determined using Formula (1) and the graphs provided in Figures 1 and 2.

 ,                   (1)

(This correlation is valid for mining depths ranging from 300 to 800 meters)

Where:

x – the distance (in meters) from the calculation point to the side drift of the dismantled chamber, located on the side of the mined-out pillar;

Z₁ – a dimensionless coefficient accounting for the width of the protective pillar between adjacent mined chambers, determined using the graph in Figure 1. If the width of the pillar exceeds 30 meters, then Z₁ = 0.4;

Z₂ – a dimensionless coefficient accounting for the type of roof up to 2.0 meters above the roof of the 4th sylvinite layer for chambers of the 4th sylvinite layer, and up to 2.0 meters above the roof for chambers of the 2nd (or 3rd) sylvinite layers. The value is determined from Table 1;

Z₃ – a dimensionless coefficient accounting for mining depth, determined using the graph in Figure 1.

Table 1.

Values of the Z₂ coefficient depending on the type of roof rock

The scheme for determining the 'roof-to-floor' convergence (shift convergence) at any point along the length (x₁, x₂, x₃… xₙ) of the dismantling crosscut, as well as the method for determining the width of the protective pillar between adjacent chambers, is shown in Figure 3.

According to the scheme in Figure 3, the total width of the protective pillar (aц) is calculated using the following formula:

а_ц = а₁ + а₂ ,  m                                                                      (2)

where a₁ – the width of the pillar(s) between the preparatory crosscuts of the chamber being dismantled;
a₂ – the width of the pillar between the unloading crosscut (or other crosscuts) of the chamber being dismantled and the transport drift of the adjacent mined-out chamber.

Figure 1. Graph for determining the Z1 coefficient depending on the width (as) of the protective seal by the adjacent chamber 

Figure 2. Graph for determining the coefficient Z3 depending on the mining depth Nr.

1 - KAZ anchors; 2 - KAMV screw anchor; 3, 4 - compensation joints.
Figure 5 - Scheme for passing and reinforcing the dismantling weld adapted to the 6th sylvinite layer

C1, C2, C3 - locations for installing wooden columns.
Figure 6. Scheme for passing and reinforcing the dismantling weld connected to the 4th sylvinite layer

The parameters for installing anchor fasteners in dismantling welds are carried out with a number of additions based on the results of studying the deformation properties of dismantling welds:

In the calculation formula for the minimal thickness of the rocks (Mmin) reinforced with KAMV anchors, the equivalent interval (bэкв) value for dismantling welds passing through the chamber weld is accepted as the width of the flat part of the roof. This width is equal to the distance from the start of the circle to the front part of the lining fastener, and bэкв = b3 (see Figure 6);

The formula for calculating the lateral bearing forces (Px) for dismantling welds is applicable up to a depth of 800 m. When the weld depth exceeds this value, the roof connection must be selected in such a way that the average compressive strength of the rocks (σусрсж) is no less than 25.0 MPa. This corresponds to the II and III types of the roof.

The reinforcement of the dismantling weld sides is carried out with 2-3 rows of KAZ (KAV(3C)) anchors. The distance between the rows should range from 0.6 to 0.8 m. The anchor spacing within each row is determined.

After the chamber lining is reinforced by the dismantling weld or after the dismantling weld is passed through and connected to the chamber lining, the expanded lining front void should be reinforced by installing wooden columns with a diameter of 0.16-0.2 m in 2-3 rows (between the lining reinforcement sections). The wooden columns must be installed within two days after the formation of the expanded lining front void. The number of columns and their installation locations, as well as the sequence of dismantling the chamber equipment, are defined in the "Dismantling Works Execution Project.

Conclusion. To enhance the stability of the roof and increase the reliability of the roof, it is recommended to leave a protective sylvinite layer before the stoppage boundary in the chamber front void, as well as to apply the technology for calculating comparative loads from the mine pressure. When connecting the dismantling weld with the roof, special sylvinite or rock salt layers are selected, which helps ensure the safety of mine operations.

The need to use anchor fasteners, compensation joints, and other reinforcement tools to improve the stability of the dismantling works has been emphasized. Additionally, these works should be carried out based on the "Reinforcement Passport," which allows full control of all processes.

In conclusion, this article includes recommendations necessary for more efficient and safe dismantling operations in potash mining. It encompasses technological methods, protective measures, and the optimal selection of reinforcement equipment. Implementing these recommendations will not only improve work efficiency but also help ensure the safety of miners and workers.

References:

1. A.V. Nikiforov, V.V. Sviridenko – "Underground structures and their strengthening", publication Nauka, 1985.
2. A.P. Anikin – "Geotechnics and methods of designing underground structures", publication: Stroyizdat, 1990.
3. G.A. Korzun, D.N. Ermolaev – "Strengthening underground structures", published: Gosgeotekhizdat, 1975.
4. S.S. Evseev – "Technology of preserving mountain structures", publication: Mashinostroenie, 1982.
5. Mozer S.P. Mining geomechanics: physical foundations and patterns of manifestations of geomechanical processes in underground mining / S.P.Mozer, E.B.Kurtukov. St. Petersburg, 2009. 136 p.