Tools for Mining: Techniques and Processes for Small Scale Mining (GTZ, 1993, 538 p.) Technical Chapter 2: Safety Techniques (introduction...) 2.1 Safety kit

Tools for Mining: Techniques and Processes for Small Scale Mining (GTZ, 1993, 538 p.)

Technical Chapter 2: Safety Techniques

TECHNIQUES APPLIED IN UNDERGROUND MINING

2.1 Safety kit

General Ore Mininig
Underground Mining Safety Technology

Mining and work safety, especially in small-scale mining in developing countries, are sensitive areas frequently characterized by major deficiencies due to cost factors or negligence. The following section presents the safety-equipment components for small-scale mining, categorized according to personnel equipment and general mine equipment. The personal safety equipment should ideally consist of the following:

Helmet - serves as the primary protection from head injuries caused, for example, by falling stones and debris, roof-falls or supports. Mining helmets are made of thermoplastic, such as PE, or fiber-reinforced synthetic resin and are predominantly produced in the developing countries. They have an adjustable inset mounted inside the helmet, with several centimeters of space left in between to accommodate a first-aid kit. The external helmet surface is affixed with a fastener for a cap lamp. The cost of one helmet ranges between 10 and 20 DM.

Safety shoes - with steel-reinforced cap and sole to protect against crushing of the toes or cutting of the foot from sharp objects. In dry working areas leather shoes are preferable, and rubber boots in wet or moist working areas. Locally-manufactured boots are available in most of the mining countries. The cost for one pair varies between 20 and 40 DM.

Ear protectors - against health-damaging noise levels such as those produced by pneumatic drilling. They are available either in the form of a head-piece with attached ear-covers, or in a simpler and cheaper form as absorptive foam-plastic ear plugs which are independently placed directly into the ear.

The following safety items are also necessary, depending upon the type of potential dangers present in the particular work-area:

Shinbone protector - protects against shinbone injuries. It consists of a hard plastic shield placed over the clothing on the shinbone and fastended with two straps.

Hand gloves - to protect hands and fingers from injury.

Protective goggles/glasses - to be worn when danger of eye injuries exists due to flying objects, stone splitters or other particles (e.g. dust from drilling or grinding activities).

Face Mask/Oxygen Mask - with replaceable filter which is placed over the mouth and nose. Especially dangerous is air-transmittable stone dust, which can cut the pulmonary alveolus in the lungs when inhaled. This disease, known as silicosis or "mal de mines", is the most common occupational disease in mining. Dry drilling, blasting and caving are activities which produce extreme amounts of stone dust, requiring not only the use of breathing masks for personal protection, but also sprinkling of the dust sources with water. In less dangerous working areas where smaller levels of dust are prevalent, a soft cloth tied over the mouth and nose frequently serves as a temporary protection.

Knee protectors/Knee shoes - these are only needed as protection in drifts of low roof height where longer stretches need to be travelled via crawling. Knee shoes are made of rubber (sometimes from parts of car tires) and fastened in place with an attached rubber belt.

Filter-Self-rescuer - In some branches of mining, particularly coal and certain salt deposits, dangers to the miner exist in the form of toxic or explosive gas emissions from the country-rock during mining underground. In salt deposits, especially those of tectonic or vulcanic origin, the accumulation of CO₂-gas under conditions of high ground pressure can lead to a sudden explosion. CO₂ is a toxic, odourless, respiration-inhibiting gas which is heavier than air and therefore collects in the deepest locations. Since the danger of gas explosion is the greatest when the country-rock is loosened by blasting, it is standard practice that blasting in underground salt mines occur during shift change in the absence of mining personnel. As a protection again these gases, every miner carries a filter-self-rescuer which allows him to escape from the toxic fumes to the surface in the event of an explosion. In coal mining, the occurrence of underground fires can likewise lead to the danger of high levels of CO and CO₂ gas in the mine air, use of the filter-self-rescuer offers protection against these gases during escape as well. CO and methane gas, emitted from the seam or country-rock, are both explosive as fire damp in certain concentrations. In order to avoid mine gas explosions, flameproof electrical equipment, permissable explosives, continual measurement of the gas content in the mine air, and extensive ventilation of the gob are necessary. Coal dust can also become explosive when present in whirling air vortexes.

Gas Measuring Devices - to measure mine gas concentrations. Measuring appratuses are available on the market either as small rechargeable electrical meters for taking single or continual measurements, or as larger measuring devices equipped with a graduated pipe and bellow pump for taking single measurements.

For the first device, the investment costs are higher, whereas for the second, the operating costs are higher. For the Indirect measurement of methane gas, gasoline safety lamps can also be used (see 6.1).

The mine safety equipment should include the following items:

Personnel tags - small numbered metal tags which hang on a check-in/check-out board near the shaft or mine entrance. One side of the board holds the tokens for those workers currently in the mine, the other side for miners who are not in the mine at the time. Every miner has a tag with his own number or name, and personally hangs it on the appropriate board every time he enters or leaves the mine. In the event of an accident, or prior to blasting, this personnel-control system allows immediate determination of which workers are currently in the mine.

Scaling rods · a basic component of the safety equipment in underground mining, used to pry off loose rock pieces from the roof and headings caused by blasting or the effects of ground-pressure. Scaling rods, like crow bars, are applied by inserting the tip in the fracture between the loosened portion and the country-rock, and prying until the loose rock falls. Old drill-rods with a sharpened tip can be employed as scaling bars in small openings or drifts, whereas lighter, longer aluminum pipes with a chisel tip are used in larger cavities. Fundamentally, scaling should be performed after every blasting round before any other activity is undertaken. Thereby, the blasted debris provides easier access to the roof. These simple safety precautions significantly Increase work safety, decreasing the risk of accidents.

First-Aid Kit - with an assortment of medicines and adhesive plasters, bandages and splints for treatment of injuries.

Stretcher - to rescue injured miners.

Gas Protection Equipment - for use by the mine-rescue team in emergency situations, these are practical in small-scale mining In developing countries only if miners are trained in mine-rescue operations. This safety measure, however, is frequently not implemented by the individual mine operators in developing countries.