Introduction

The US has one of the largest mining industries in the world – an industry closely linked with the economy. In the past, the discovery of resources such as gold and oil resulted in a major population shift and rapid growth for formerly remote regions of the country, such as California, Texas, and Alaska. Extraction of these resources, and finding new deposits, continues to provide the foundation for local economies in some regions.

Some of the minerals mined in the US are coal, uranium, copper, gold, silver, iron, lead, zinc and others. Most of the mines in the US are highly automated and thus energy intensive. To provide an example, even in the last decade of the 20th century, iron ore mining alone consumed 62.3 trillion Btu of energy across a calendar year. Because mining is such a large industry and makes a sizable contribution to the national income, mines must have a dependable source of power – a crucial resource for mining processes.

The mining and mineral extraction sector both in the US and worldwide relies heavily on energy to harness natural resources such as aggregates, precious metals, iron ore, oil, gas, and coal. This energy is used to power shovels and drills for excavating these products, loading them into enormous mining trucks or onto conveyer belts, sorting, sifting and crushing ores, heating, and a hundred other functions. Both surface and underground mining operations rely on powered equipment to extract materials and load trucks. Overall, the mining sector could not flourish without the use of vast amounts of energy.

The Role of Transformers

Mine ‘Power Centers’ or ‘Load Centers’ are an essential system for underground and surface mining. Their primary function is to convert distribution voltage into utilization voltage for equipment operation, thus placing power transformers at the heart of the load center. Proper selection of transformers is imperative, and must fulfill safety, reliability, and efficiency requirements. Determining capacity rating is among the first steps for selection of a power transformer for a mining load center. A rule of thumb here is to allow 1 kVA for every horsepower of connected load. Most mining processes, however, do not produce constant loads – all machinery is not connected all the time – and therefore the 1 kVA per horsepower thumb rule will typically result in transformer oversizing. According to the SME Mining Engineering Handbook by Howard L. Hartmann, “Past experience and demand factors established by manufacturers and operators, along with the horsepower of the connected load, are essential for determining transformer capacity. For typical underground mining sections, the kVA rating may lie within the range of 50 to 80% of the connected horsepower.”

Transformer Losses

Standard transformers while under full load operate at 90 to 95% efficiency, with this figure dropping as the load lightens. This is due to inefficiencies in the transformer’s core, a main component of the transformer. The losses in the core remain the same throughout the transformer’s operating range. At 100% load, the amount of comparative loss is negligible. However, at reduced loads, the same amount of energy loss represents a higher percentage of energy being wasted. Unfortunately, average transformer loads run between 34 and 50% of the transformer’s total capacity. With the majority of the electricity used

in the US being run through transformers at these lower loads, massive amounts of energy are being wasted. This issue is of special relevance to the mining industry, simply because of its high energy usage. Mining operations also involve hostile environments full of dust, dirt, chemicals, moisture and airborne contaminants. Load center transformers need to function reliably and efficiently in these environments over a long term.

Without electric power at mining facilities, the natural materials extracted from the earth in the mining process would be much more costly than they are today. Thus, power transformers provide a lot of muscle, capacity, and stability to an essential industry. From drilling trenches to busting up rock, carting out huge loads of materials and pulling up heavy amounts of minerals, power transformers provide the strength and capability needed.

Liquid Filled and Dry Transformers: Performance Characteristics

1.Liquid-Filled Transformers

While there is still debate on the relative advantages of the available types of transformers, there are some performance characteristics that have been accepted: • Liquid-filled transformers are more efficient, have greater overload capability and longer life expectancy. • Liquid-filled units are better at reducing hot-spot coil temperatures, but have higher risk of flammability than dry types. • Liquid-filled transformers sometimes require containment troughs to guard against fluid leaks. • Liquid filled transformers are smaller in size than dry-type units for the same power rating capacity and have lower losses because of their better thermal dissipation characteristics.

2.Dry Type Transformers

Dry type Transformers are usually used for lower ratings (the changeover point being 500kVA to 2.5MVA). They are usually placed indoors, serving an office building/apartment. Dry type units typically come in enclosures with louvers, or sealed.

Dry type transformers use almost no flammable materials and therefore do not constitute a fire hazard when used underground in both coal and other mines.

Dry type transformers in the mining industry are housed in a steel tank and the core and windings are cooled by air circulating within the tank, transferring heat to the steel tank which is in turn cooled by the external air. In some compact designs for mounting on mining machines water cooling is added to further improve the performance of the transformers.

Correct choice of insulating materials and an understanding of the cooling system is imperative if the transformer is to be correctly designed. For example, a temperature rise test conducted on a transformer manufactured and sold as continuously rated, can reveal that the transformer only had a continuous rating of 65% of the nameplate rating.

The Need for Energy-Efficient Mining

With the current focus on climate change and reduction of environmental impact, government agencies around the world are making increasingly stringent demands on industries to reduce energy consumption and manage waste more effectively, among others. It is surprising how many mining operations still use twenty-year-old technology.

Regulatory pressures are already beginning to affect the mining industry – according to an article on ‘US Environmental Regulations and the Mining Industry’ on the International Development Research Center (IDRC) website, “Environmental regulations have had an effect on the US mining industry’s profitability. Companies have been forced to retrofit or renovate installations or leave the market. Increasing operational costs have affected their international competitiveness, and to some extent, this may be changing the world allocation of mining investment. Employment levels have fallen substantially, and local economies have borne part of this cost.”

Mining companies in the US are thus feeling the pressing need to be energy-efficient, simply to stay competitive. Reducing energy consumption by adopting customized, cost-effective solutions like NEMA-approved transformers and harnessing solar or wind energy to meet their future energy needs can be good ideas in the long run, especially since the alternate energy option will help mining companies keep away from fluctuating international fuel prices. Alternate sources of energy are still a very small blip on the graph, in terms of actual power provided for industries like mining, and thus the sector as a whole needs to come up with more immediate ways to conserve energy.

Various types of transformers for the mining industry:

Transformers can be used in various open pit and hard rock (subterranean) applications that range from auxiliary lighting loads to power for cranes, drag lines, conveyor belts and other miscellaneous dedicated variable speed drive applications.

Benefits of energy-efficient mining
• Reduced cost of production
• Opening up of new reserves for Conclusion

On one hand the mining industry is all set to grow to keep up with increasing demand; on the other it has to stay competitive as fuel prices zoom upwards. For an energy intensive industry, keeping a check on fuel consumption and cost is critical. Thus the mining industry as a whole is looking for energy efficient technology, including power transformers.

It’s also important that people wanting to enter the industry have relevant experience in the area they want to enter in the Australia Mining industry. The market is getting very competitive with some companies getting over 500 applicants or more for one position. Especially with the amount of media that the mining industry is receiving on current affair programs in Australia and New Zealand regarding all the money to be made in the industry. It’s making it a lot harder finding position, especially unskilled mining jobs and also finding companies that will take on people with no previous mining experience. It’s not as easy as it used to be in entering the mines. More work is being mechanically assisted therefore skilled people are required rather than the old days in the industry when a lot of unskilled positions were available.

Also certain skills and trades are in more demand than others. Mothers and Fathers reading this should take some notes and direct your kid in the right directions when they are planning to leave school and enter the work force or university study. If your kid is not interested in university study and wants to leave school get them into a training scheme with a company that will give them a trade after a few years that will in return earn them over 100,000 a year and only working two thirds of the year in the mining industry in Australia. Also university study can be planned and the end result will be more rewarding. Students with a Mining Engineering Degree’s are getting snapped up quicker than they are being graduated. There is an 18% vacancy rate in this area and top students are getting sign on agreements of up to 10,000 dollars like sporting super stars with some of the large mining companies in Australia as well as a 100,000 starting off salary.

Getting back to relevant experience; Mining companies want to hire people that have done the particular job back in the cities and are passionate about their job. Its costs a lot hiring a person, and putting the person through the inductions fully paid and then ongoing training, the last thing they want is the person to quit their job after a few weeks.

A lot of people tell me they have an HR and want to drive trucks? But they don’t have any experience driving trucks in the city let alone on a mine site. Agencies won’t even look at your application if you don’t have mining experience of 2-3 years. A lot of their positions are fly in fly out and are filling a vacancy that is important for production to run properly. If production is not running efficiently, it’s going to costs the company money. A lot of the big companies don’t have time to train people on the job site any more. This is the same with people wanting to enter the industry as a cleaner on a mining camp. The hiring companies want people are experience in this field as its costs them a lot to train people and put them through inductions. If people have several years experience in this field, it shows the company they are passionate about this job as they want people that are going to stay with them for a long time and are not just using a cleaning job in a mining camp to gain a dump truck job. This is a big NO for the hiring cleaning companies in the mining industry and they have tough interview procedures to stop people entering the cleaning industry with the intention of fining a dump truck job.

The way the mines are going you want 2 -3 years experience in a field in your civilian career. If you want a particular job in the mines its best to start now where you live and get some experience. Even if it means driving buses, it’s still related to driving trucks. Bus drivers make good dump truck drivers as they have to be safety conscious during the day which skill is wanted for dump truck drivers to have. This is the same for people that tell me they have driven a digger a few times in the past and planned to get a job driving a digger on a mine site. Hope you have good patience as if this is the only experience you have your going to be waiting for a while. Those diggers on the mine sites are a lot bigger 150 – 700 tonnes. These positions driving dump trucks and diggers are paid well and the employees climbing the company ladder will be getting these positions before you.

It may be easier to find a job with a small sub contractor company that has work on a mine site. They may not pay as much as the big mining companies but they are more likely to hire a person in your situation and this way you get that valuable mining experience.

A lot of the time is who you know in the mining industry, if you met the right people and make a good connection with them. It’s easy to find a job any field you like.

There are three job fields in the mining industry in Australia:

University educated mining jobs. Geologists, mine managers etc. Jobs that require university study as important part of the position.

Skilled Worked. Mechanics, wielders, Boiler makers, Drillers, Often requiring a trade or specific training.

Ticket required Jobs. Loader driving jobs, Truck driving, Road trains and dump trucks. Jobs often requiring tickets to show you’re skilled in driving particular machinery or vehicles.

It sometimes turns into a cache 22 situation. The companies only want to hire experience people but how do you get that experience if they don’t take new comers to the industry on. Answer; 1) Use your friends if you have any that are working in the mines. 2) Some companies run programs in participation with training institutions in the cities where if selected after a 1hour interview you can do one of there courses and then they help you get a job. These organizations can charge up to 4000 dollars and some applicants have waited 4 months for a position. This is very common for the people entering the industry wanting to drive dump trucks. 3) The last option is to take up another position in the mines which provides easy and quick access to get that “mining experience” that companies want. It may not be a position that you want to do for the rest of your life, but it’s a position that pays wells and will open the world to the lucrative mining industry.

All About The Story of A Dump Truck

Technically speaking, a mining truck can be categorized as one of the variants or modifications or versions of the universal dump trucks. For very obvious reasons, these heavy wheels are designed to take weighty loads on their backs. To classify a bit these mining machines, these can be considered as off-road dump trucks.

As indicated on their general title, these wheels are designed to haul or carry heavy dirt and mining loads are intended to be off the road. On the other hand, some mining industries or corporations around the world do not use the word ‘dump’ on their mining trucks these days. However, these heavy dirt hauling machines have two main types and they are the articulating frame and the rigid frame.

Getting Some Measurements and Sizes

Though these dump trucks are now officially accepted as ‘haul trucks’ especially in the United States, the functions of these mining trucks are almost the same. Believe or not, these burly hauling wheels can carry from a hundred to 300 tons of load. Following this line of thought, these ton-carrying machines are even assembled within the mining site because of their colossal sizes and proportions.

One of the largest mining trucks has 7.9 meters (or more or less 26 feet) in terms of its broadness, a twenty-meter span (or 67 feet) in length and weighs about 231105 kilogram or 509500 pounds. This hauling or dump truck model Titian or the 33-19 was made by General Motors (or GM) during the early 1970′s. This particular machine has a whopping hauling capability of up to 350 ton-load. To support its overall weight plus its load, this machine has ten tires that measure 3.4 meters in diameter each (or about 11 feet in diameter).

Though the Titian or the 33-19 is big, the one from Caterpillar is the Biggest

If size does really matter, then the Caterpillar 797 model is the biggest amongst these mining trucks. Created in the late 1990′s, this truck has a loading capacity of 360 tons and an overall (or gross) weight of almost 544310 kilograms or 1.2 million pounds. This huge mining truck has a mechanical drive and an auto power gear diffusion.

These heavy machines may have been created almost a century ago. Nonetheless, their value, in terms of what these machines can do or literally ‘carry’ is really priceless. For this reason, these heavy wheels should be taken care of properly to maximize their usage.