Mining is the extraction from the Earth of precious raw materials or other geological materials, typically from an ore body. Mining ores contain coal, shale, gemstones, limestone, chalk, dimension stone, metals, gravel, salt, and clay. Mining shall be necessary to extract any material which cannot be cultivated by agricultural processes or which may be artificially manufactured in a laboratory or factory. Mining in a general context entails the production of some non-renewable resource, such as coal, natural gas, or even water. Modern mining processes include the prospecting of ore bodies, the study of the possible benefit of the proposed mine, and the extraction of the desired raw materials. Also, it’s utilized by various industries such as Cement Manufacturing Industry, Steel Manufacturing Industries, Ferrous Foundries, etc.
A raw material also knowns as feedstock is an unprocessed/basic material used for the manufacture of commodities, energy, finished goods, or intermediate materials as the main substance. As a feedstock, the term signifies that these materials are bottleneck assets and are needed to manufacture other goods.
The most significant aspect of the mining process is the raw materials which is used to produce bricks. The consistency of the brick and the progress or loss of the brick plant can also be traced back to the raw materials. The preparation and development of raw materials is the foundation of a well-run brick factory. Brick plants are also constructed close to the main raw materials that have been used for decades. Normally, the nature and durability of these raw materials differ across the entire mine. If the characteristics of any of the extracted materials are so far away from the requirements, it could be appropriate to avoid those raw materials, thus reducing the stocks of raw materials.
A few of the characteristics and ways to maximize the use of raw materials are listed below.
The following are the characteristics of the raw materials:
- Contaminants: Contaminants including carbon and sulfur, soluble sulfates, lime, and iron pyrite may be contained in the raw material. These pollutants can lead to common briquette problems such as bloating, black core, scumming, efflorescence. These concerns may be seasonal since pollutants may exist within a mining season and their intensity can differ based on the degree of contamination. Black core and bloating can be accomplished by non-plastically opening up the brick body or by changing the firing curve to encourage oxidation.
- Sand Content: Throughout a geological formation, the sand content of a raw material can differ. Any particle larger than 75 microns is known as sand. The particles in the sand scale are non-colloidal and can help decrease shrinkage. For a brick body mix, the required range of sand-sized particles is 30 – 35 percent. Designed mining can help keep the raw material mix within specifications using the weighted average values for particle size.
- Clay Content: Clay is defined as having less than 2 microns of particle size. Such particles account for the shrinkage and strength of the dry and fired brick in a clay body. Clay-sized materials are typically colloidal and have additional properties that contribute to the behavior of brick raw material mixes, such as plasticity. For a brick mix, the desired range of clay-sized particles is 40% to 45%. Designed mining can help keep the raw material mix within specifications using the weighted average values for particle size.
- Silt Content: Silt is defined as being larger than 2 microns and smaller than 75 microns in particle size. These particles may be colloidal, which may lead to shrinkage. As drying problems and unpredictable characteristics are common, raw material mixtures with high silt content sized particles can be difficult to use. For a brick body mix, the optimal range of silt sized particles is 20 to 25 percent. Designed mining can help manage the raw material mix within specifications using the weighted average values for particle size.
- Shrinkage: The raw material reduction during drying and firing processes is to be understood to meet the size requirements for the fired brick. In certain brick plants, the size of the dry brick is essential, as the fitting machine is built to accommodate and maneuver the specific size range. Too large or too little, dry bricks are difficult to be managed. The fired shrinkage and subsequent overall shrinkage must be known to meet market expectations for the resulting brick. Shrinkage may be tested partly by non-plastic materials, for example, calcined clay or sandy materials.
- Fired Colour: The relationship between the occurrence of high-temperature crystalline phases and the colour of clay bricks after being fired under oxidizing conditions at 1832°F. The colour of the fired clay will specify the body colour of the finished goods. This is highly important when bricks are used in commercial buildings where the colour has been deliberately picked. Colours may be handled by carefully blending various raw materials or by using natural or formulated pigments.
Enhancement and Diversity:
Complete utilization of raw materials from a mining site is the main target when extracting raw materials. A written strategy can be drawn up that would use a variety of raw materials to produce quality bricks through some research & characterization of its properties. Mine management can be achieved that results in the ideal colour, remove contaminants, and includes the correct ratio of sand, silt, and clay particles.
Plans for the use and optimization of raw materials will also lead to ample variance to adversely affect the brick quality. The composition of the sand, silt, and clay may differ, which can result in a raw material mix that is less than refined. Particle size ratios not defined can result in poor extrusion, low plasticity, and low green-dry strength.
Improvement of Raw Material:
It could be appropriate to strengthen raw materials with a binder and/or plasticizer to exploit the whole mining field. This can make marginal mixtures of raw material much better than without the use of an additive. By using the appropriate dose of a clay conditioner, a brick plant will extend the reserves of clay by continuously performing well on the marginal material.