Boral Quarries produces a range of useful materials based upon stone and rock. Suitable rock is extracted to make construction aggregates such as crushed rock, sand or gravel. These abundant yet essential raw materials provide the literal foundation of our homes, schools, hospitals, roads and almost all aspects of the built environment we depend on.
What is Quarrying?
Quarrying is the extraction of natural resources from the earth, usually from some form of surface workings.
How does Quarrying take place?
Simply, a quarry ‘pit’ is dug to access the identified rock deposit. Once the vertical face of rock is exposed, large chunks are dislodged, usually through controlled blasting.
The dislodged rock is then crushed into aggregate form, impurities removed, then graded by size before being stockpiled. The aggregates are then transported by road or rail for use in civil construction, mainly through the production of concrete. Sand is another important ingredient of concrete. It is quarried simply via removal from an open pit with an excavator. It is then ‘screened’ and washed before being transported for use.
What is Blasting?
There are a number of ways to extract ‘hard’ rock, but the most common and effective method is ‘controlled blasting’. Blasting is a very precise and carefully planned operation that involves drilling into the rock in a specified pattern, then placing explosives in the holes. The explosives are then detonated in a precise sequence, designed to maximise the efficiency of rock breakage while minimising noise, vibration and dust. One of the advantages of blasting is that it reduces the need to operate large heavy equipment to extract the rock, in turn reducing noise and greenhouse gas emissions. Depending on how close you live to a quarry, you may notice some vibration or noise associated with blasting. Your individual response to a blast will depend largely on the vibration’s magnification, duration and frequency. However, because the vibration magnitude varies from site to site, no common threshold exists. Your age, health, and to a large extent, previous exposure to similar blasts can be influencing factors, as can the activity you’re performing at the time of the blast. For example, a person walking is less likely to feel vibrations when compared to a person sitting still.
What safeguards are in place during blasting?
Strict national safety regulations apply to protect neighbouring homes, buildings and public places from the potential effects of blasting. Blasting operations must adhere to prescribed limits stipulated by the relevant regulatory authority that are well below the vibration levels which could cause structural or cosmetic damage. Blasts are monitored at different locations with sensitive ground and air vibration equipment to ensure they remain within regulations.
What else should I know about blasting?
Apart from vibration, the energy used in blasting to move and break rocks may also result in some noise and dust. The further you are away from the quarry, the less you will notice these effects. A quarry’s strict operating conditions requires that every action be taken to reduce these effects.
Why do we need Quarrying?
To build our homes, workplaces, public buildings, roads and the other infrastructure upon which we rely, we need stone, gravel and sand. Quarries are vital to the building and construction industries and directly employ more than one million Australians. The building and construction industry needs more than 150 million tonnes of construction aggregates each year. As well as providing these essential materials, quarries stimulate local communities through investment and by providing jobs. The quarry industry creates more than 10000 jobs directly and supports another 80000 indirectly, often in rural and regional locations. Quarrying is also vital to the production of concrete (link to concrete information), Australia’s most used building material.
Selecting a Quarry Location
Stone, sand and gravel are naturally occurring materials and their location is determined by local geology. A quarry must therefore naturally be placed where these resources are located, and also near efficient transport routes. Well before a quarry is established, extensive planning and development activities are carried out to determine the best way to develop and manage it, and to minimise any effects the operations may have on the environment and local community. Once the quarry is approved and operations have commenced, it must satisfy stringent operational and environmental regulations. Regular monitoring is undertaken to ensure compliance.
Extracting the rock
The process starts by breaking off large chunks of rock from the quarry walls, usually through controlled blasting. The rock is then moved using loaders and trucks to a primary crusher.
What is the Primary Crusher?
The primary crusher reduces the overall size of the material to make it easier to process. It’s then transported via a conveyor belt for further processing.
What is Secondary Crusher?
A secondary crusher can reduce the material’s size again, and some sites even have a tertiary crusher as a third processing point. The resulting crushed rock is then put through a sorting or screening process to ensure the final aggregate is of the correct size and shape, and is also clear of impurities.
Storage and Transport
The aggregate is then ‘stockpiled’ and transported to concrete batch plants or other local construction sites where required.
How do Quarries keep building costs low?
Quarries are usually long term operations and often serve the needs of the community for many years. Extensive planning is required to balance any local effects while serving the need for the construction of infrastructure. Quarries must be located where the rock resources are found and where existing transport infrastructure, road or rail, is available to get the materials to market. The closer a quarry is to its markets, the cheaper the cost of supplying the materials. The end cost savings flow through to the cost of constructing homes, driveways, paving, roads and all other facilities our communities rely upon. Because the trucks delivering these materials have fewer kilometres to travel, there are fewer trucks needed, resulting in less wear and tear and congestion on our roads, reduced risk of collisions, and less CO2 emissions.
How are Quarries rehabilitated?
Quarries are usually long term operations and often serve the needs of the community for many years. As resources are extracted and exhausted, the quarry is progressively rehabilitated to either return it back to as close as possible to a natural state, or to prepare it for secondary uses such as residential or industrial, or recreation.
A rehabilitation plan is usually determined as part of the quarry approval process and can involve replacing the original topsoil, replanting local vegetation, or reinstating particular habitats.This is a continual process as operations move from one section of the quarry site to another.
Boral Quarries can be found throughout Australia. Click here to find out more.