When it comes to the mining industry, focus on safety for workers and machinery is higher than ever. Still, mining is amongst the most dangerous industries in the world to work in. There are many reasons for this. Difficult work, long hours, routine movements which lead to misjudgment, faulty operations, and simple human error on machinery are just a few. Heavy machinery can be working 24-7 and often only receive service when absolutely necessary. In addition, the weight of the handled material can be extreme and accidents can result in serious injury or, in the worst cases, even death.
Lifts, cranes, drills, bulldozers, conveyors, and milling machines are all critical machinery for the process of handling tons of rocks, coal, and ore every hour around the clock, but they are also powerful and dangerous machines if not handled properly. A 10-year study on mining accidents from China shows that 94% of the mining accidents were due to the human error, with a stunning 55% due to mismanagement of equipment and 35% due to intentional violations.
In other words, a high majority of the accidents were due to the human-machine interactions. All of these situations can cause breakdown of production, which can cost thousands of dollars, but aside from the cost factor, it is important to understand and respect the danger that miners are put to when the human error occurs.
Modern machinery will normally be equipped with the necessary control and safety tools securing personnel and machines from human errors. These instruments still need service and monitoring, however, there are thousands of old “well used and well running” machines in use in the mining industry. Machines that have been working for years but have developed little errors over the years due to wear and tear. Instructions such as “you have to know it” or “be careful when you….” often come with these machines, but a machine that is both effective and safe to use should never come with warnings like that.
Let us look at six very reasonably priced instruments that will make the work safer for the personnel.
- Cranes and hoists moving into restricted areas can put personnel in danger. Many cranes can overtravel and thereby cause damage to both the crane and surrounding equipment. This is a commonly known issue caused by human error and it can be avoided by installing a limit switch or rotary limit switches on the crane. These simple mechanical instruments will monitor the motion in progress and limits can be put in place eliminating almost 100% of all “out of position” type of incidents. It simply stops the crane or hoist before the dangerous situation occurs.
- Moving cranes are equipped with brakes and, much like a car, these brakes need to be changed. This needs to happen on a routine basis before the brakes stop functioning. Brakes for cranes are electrically released and spring set for safety. On magnetic industrial brakes the electrical mechanism consists of one or two DC coils. As power is introduced to the coils, it creates an electromagnetic field that releases the brake. Cutting power to the coils allows the spring to extend back to its original position and sets the brake.
- Hydraulic hoses, and power or signal cables are usually an unforeseen danger. A broken hydraulic fluid hose may cause a burst of 100°C fluid spraying out at over 300bar. The consequences for the colleague standing nearby could be crucial! Focus on safety and efficiently conveying power by protecting the cables and hoses is pivotal in the mining industry. The cables and hoses deliver power, air, or hydraulic (or a combination of these) to mining equipment in motion. This is critical to the operation of most equipment and the best protection secures the hoses and wiring from abrasion, wear and twisting.
- The hydraulic cylinder controls the extremely heavy equipment used in mining. It also controls where the drilled ore will fall from the excavator. Knowing the position of these cylinders at all times is important to avoid shovels or drills from getting out of balance. Position monitoring is often performed by linear displacement transducers (LDT). These are installed on the machine to help automate the process and guide the operator, and thereby minimize the risk compared to the process where manual handling alone is used. Some machines use the LDT to measure the deflection of the shovel boom to eliminate the risk of lifting a shovel that is too heavy. Lifting a shovel that is too heavy can not only break the machinery but also increase the danger when an excavator tip over.
Retrofit type solutions can increase product and personnel safety significantly at a reasonably cost on out dated but still well running machinery. An LDT is typically mounted inside the cylinder to provide the best protection of the electronics, but on older hydraulic cylinders, the inside mounting may be too difficult. As a result, some LDT’s can be mounted on the side of the cylinder providing virtually the same accuracy.
It is not crucial whether or not the LDT is mounted inside or outside the hydraulic cylinder. What is crucial though is to make sure that it is a high quality LDT that is installed, so it is able to withstand the constant vibration and shock that is very common on these machines.
- Dusty environments are extremely hazardous. The combustion level of dust, and especially of coal dust, can create an explosive atmosphere, where the slightest spark will create a potential disaster. Using IEC 60079-11 certified products has been the safety standard in South Africa since 2005. Make sure to avoid mistakes that can cause the mounting of non-IECEx approved products, or even non-grounded products such as lights, drills or pumps.
For some areas, using a simple grounding reel can be enough to avoid explosions. Rugged grounding reels using static grounding cords and clamps can secure the grounding, and thereby the work safety, in accordance to the individual hazardous zone classification.
- When storing or moving materials, it is important to be able to continuously measure the stream or amount of material to avoid accidents due to overload. Non-contact position sensing solutions, such as radar level transmitters, have been proven performers in the mining industry for many years. Quick response times and state-of-the-art electronics make this technology an excellent choice for fast moving material. Overfill prevention and ensuring clearances on large and heavy materials is paramount in keeping the work environment safe.
Installing these instruments on heavy machinery may enhance the longevity as well as lower the number of breakdowns. But at the end of the day whether one is mining for coal, gold or anything else, safety should at any given time be first in line. As the study from China clearly states, humans make mistakes. It is the responsibility of any company to minimize the risk of human errors, and to do so by educating the personnel as well as using simple technical instruments.