For years, quarry operations have depended on blasting to extract material that lies below several layers of unneeded rock and overburden. However, as mine operators face an increasing number of restrictions on blasting, many are seeking alternative methods – such as selective mining.
As opposed to blasting, where mines break free large amounts of rock and then sort out the good material from bad, selective mining allows the desired aggregate to be extracted while removing only a small amount of unusable rock. Selective mining gives quarry operators optimum control of resources by removing only material that holds value and that the mine is licensed to extract.
Breaking into Mining
One common method of selective mining is breaking, which involves using a hydraulic breaker to chip away at the desired deposit of rock, producing a stream of material. Over the past decade, breaking has become very popular in Europe, where population density and strict government regulations on blasting have forced mine operators to either close down their mines or develop alternative methods for extracting material.
Many American quarries are currently using hydraulic breakers for secondary breaking, but as laws affecting mining continue to multiply and equipment manufacturers develop breaker technology for mining applications, breaking as a primary method for extracting material will gain popularity as well.
Breaking is becoming common as increased regulations make blasting difficult or impossible. One issue is that cities are growing close to mines, and the shock waves, flyrock and noise created by blasting can impact civilian safety and quality of life. Before manufacturers designed breakers large enough to replace blasting, many mines near populated areas were forced to close. However, the larger hydraulic breakers now available have allowed several sites to re-open.
Blasting can also disrupt many animal habitats, and the dust produced from blasting — along with the ammonium nitrate and fuel oil mixture in many explosives — is often associated with air and water pollution issues.
Concerns about mine personnel safety also add to blasting restrictions. Mine employees are susceptible to injury from the explosives themselves or resulting debris. Safety concerns make explosives expensive and hard to use, due to close government control. Quarries must spend a lot of money to ensure their operations comply with employee safety regulations.
In addition to providing an option where blasting is prohibited, breaking can be a good choice for mines looking to increase productivity, minimize costs and improve product quality.
Because blasting can uncover more material faster, it’s difficult to believe breaking can actually increase productivity. But by eliminating interruptions for blasting and clearing, breaking allows quarries to continuously operate and bypass the secondary breaking process. A hydraulic breaker produces a steady stream of rubble that a single loader can then carry to a conveyer belt, which transports the material to the crusher.
This system also saves money by reducing personnel and equipment. In contrast to the minimal equipment and manpower needs for breaking, blasting requires a hydraulic breaker for secondary breaking, wheel loaders to load trucks, and several trucks to haul rubble to the primary crusher. The wages of operators, along with costs for purchasing and maintaining large equipment, are expensive. Breaking can further reduces costs by downsizing or eliminating the primary crusher.
Reducing waste material also decreases costs. Mine operators don’t have to sort blasted material and haul out unwanted portions. Also, because blasting can be prohibited where breaking is allowed, mines using breakers often obtain more yield from their approved mining volume.
Breaking further increases the usable mining volume by reducing fines – small pieces of material too small to sell. Because breaking gives operators more control over the size of the particles they extract, the result is fewer fines and more usable material. Furthermore, when a mine blasts, small waste particles will often mix with the usable material, decreasing its quality and value.
The cost of mining also decreases with breaking because there is no longer an investment required to store and use explosives. Strict facility and security measures govern how explosives are stored, and many mines will spend large amounts of money on explosive storage facilities and security personnel.
There are also simpler approval procedures attached to mines that use breaking. Because breakers are less controversial than traditional blasting, breaking often simplifies the mining permit renewal process, which can save mines significant time and money.
Making the Switch
Although breaking is perfect for some, it is not the solution for all. Each quarry is different, and many issues need to be considered to determine if breaking is a good alternative for a given location. While some mines may find that breaking is an ideal option, others will discover that using breakers only for select applications is the most economical choice.
Whether quarries turn to breaking to save money, to increase product quality or to comply with regulations, it is certain that in the future several operators will need to find an alternative to blasting. And, with hydraulic breaker manufacturers continuing to develop technology for the mining market, more and more mines will view breaking as a plausible and productive option.
(Kevin Loomis is Hydraulic Attachments Product Specialist for Atlas Copco Construction Tools.)