Mining Handbook. Volume 4, Underground Mining

Author: Chief Editor: Jieshijun
Publisher:
Publish Date: 1999-09-01
Features: The Mining Handbook is divided into 41 chapters and published in seven volumes:
Volume 1: Mine Geology and Mine Surveying
Volume 2: Blasting and Rock Support
Volume 3: Open-Pit Mining
Volume 4: Underground Mining
Volume 5: Mine Transport and Equipment
Volume 6: Mine Ventilation and Safety
Volume 7: Mine Management
This volume is the fourth, covering eight chapters: Mine Development, Classification and Selection of Mining Methods, Open Stoping, Fill Mining, Subsidence Mining, Pillar Recovery and Void Treatment, Ground Control in Mining, and Mining under Special Conditions. This book is primarily intended for mine mining engineers, but it is also an important reference for researchers, designers, educators, and mine management personnel involved in mining.
Excerpt:
Large proportions. Underground mines with greater depths are typically developed via shafts. Currently, mines using single-rope single-section hoisting generally have lifting depths of about 500–600 meters, while those using multi-rope single-section hoisting can reach depths close to 1,000 meters. In foreign countries, due to the use of Bremer hoists, single-section hoisting depths have reached up to 2,440 meters. For shaft-developed mines, since shaft deepening is complex, it is essential to excavate the shaft to an appropriate depth during construction to ensure sufficient mineable reserves for the mine's normal production over a reasonable period. The initial shaft excavation depth depends on the ore-dressing system, with small mines retaining 8–10 years of reserves and large mines retaining 10–20 years. However, it should not be excessively deep, as this would increase investment, delay mine commissioning, and hinder capital turnover. Based on the relative position of the shaft to the orebody, shaft development can be categorized into three types: footwall, lateral, and hangingwall. Shaft development through the orebody is rarely used.
17.5.1.1 Shaft Development Methods
A. Footwall Shaft Development
Footwall shaft development is the most widely used method in shaft development. For mines with long strike lengths, especially large-scale ones, to optimize underground transport, mining sequences, production allocation, ventilation, construction speed, and tunnel maintenance conditions, the shaft should be located in areas with minimal transport requirements or near such areas (see Figure 17–14), provided the site, terrain, and engineering geological conditions permit. This approach ensures better economic benefits for the mine.
B. Lateral Shaft Development
When the orebody is constrained by site, terrain, or engineering geological conditions, making it impractical to establish facilities on the footwall or the existing site is already on one limb of the orebody, lateral shaft development can be adopted. It is also suitable for short-strike-length orebodies with small-scale development to reduce the number of shafts and simplify transport and ventilation systems. When using lateral shaft development, both limbs of the orebody, especially the one with the hoisting shaft, must be thoroughly explored. Examples include the Jiajiazhangzi Coal Mine Bureau's Qianqi Mine and the Qili District of the Hongqi Ling Nickel Mine (see Figure 17–15).
C. Hangingwall Shaft Development
When the footwall and lateral limbs are unsuitable for facility construction, facilities must be built on the hangingwall (see Figure 17–16); or when the orebody dip is nearly vertical or horizontal, and shaft development on the hangingwall is advantageous for site location and external transport, with lower construction investment and operating costs compared to the footwall, hangingwall shaft development can be adopted. Compared to footwall and lateral shaft development, hangingwall shaft development has the following disadvantages:
- Longer initial adits, resulting in larger construction projects, longer construction periods, higher investment, and poorer economic benefits upon mine commissioning.
- If the shaft passes through the orebody, these disadvantages can be mitigated, but it requires leaving (safety pillars), making it generally impractical.
17.5.1.2 Classification of Shafts by Hoisting Container
A. Manhole Shaft
Manhole shafts can transport ore, waste rock, personnel, equipment, and materials, as well as serve as an air intake shaft. They are versatile but have drawbacks such as low hoisting capacity, complex loading/unloading of mine cars, high labor intensity, and high hoisting costs. Therefore, they are often used in exploration shafts and small mines, or as auxiliary shafts in medium and large mines. They are also suitable for ores with cohesion or tendency to agglomerate, which are not suitable for chute ore discharge or skip hoisting, or for ores that should not be excessively crushed. When used as the primary hoisting shaft, due to multi-purpose use, sufficient margin must be reserved in production capacity calculations to ensure normal mine operations. When used as an auxiliary shaft, existing mines often use it for waste rock hoisting, which can lead to heavy and demanding auxiliary shaft tasks. New mines should, where possible, avoid waste rock hoisting and use the shaft only for personnel, equipment, material transport, and air intake. Manhole shafts can use single or multiple cages for hoisting, depending on the ore volume. For small production and multi-stage ore hoisting, a single cage is sufficient. When using one hoist to lift two cages, to improve hoisting capacity, centralized single-stage ore hoisting is preferable. As auxiliary shafts for medium and large mines, single-cage hoisting is commonly used. Large and extra-large mines, whether as primary or auxiliary shafts, should also have small traffic cages in addition to large cages to save energy, reduce costs, and facilitate management personnel's access and emergency hoisting.
B. Skip Shaft
Medium and large mines, as well as those with complex mining conditions, often use skips for ore hoisting. Skip hoisting systems have high capacity, efficiency, and low costs but involve substantial engineering work and high investment. Skips can also transport waste rock in addition to ore. Using skips for waste rock hoisting reduces the burden on auxiliary shafts and simplifies their loading/unloading facilities. Mines with large waste rock volumes may also establish dedicated waste rock skip hoisting systems. In mines using skip hoisting for ore, the skip shaft serves as the primary shaft, while the manhole shaft (or inclined ramp) serves as the auxiliary shaft for personnel, equipment, and material transport. The manhole shaft (or inclined ramp) can be centrally or decentralizedly arranged relative to the skip shaft. When centrally arranged, the distance between the main and auxiliary shafts should not be less than 30 meters. Centralized arrangement offers the following advantages:
(1) Concentrated industrial site, saving land area, simplifying surface and underground yard layouts, reducing surface and underground earthwork and investment, and facilitating production management;
(2) Facilitating construction, shaft deepening, fine ore recovery, and centralized drainage;
(3) Consistent underground transport and drainage directions, benefiting tunnel construction.
Therefore, as long as site layout permits, centralized arrangement should be prioritized. Examples include the Taolin Lead-Zinc Mine and the Gongchangling Iron Mine. Only when constrained by site, terrain, waste rock disposal, or excessively long auxiliary shaft adits should decentralized arrangement be used. Examples include the Tongguanshan Copper Mine (Figure 17–13) and the Anqing Copper Mine. In centralized arrangement, stage adits can directly connect to the main and auxiliary shafts; in decentralized arrangement, stage adits connect only to the auxiliary shaft, with only a few stages connecting to the main shaft.