What is Calcium ?

Calcium is the chemical element with the symbol Ca and atomic number 20. It has an atomic mass of 40.078 amu. Calcium is a soft grey alkaline earth metal, and is the fifth most abundant element by mass in the Earth's crust. Calcium is also the fifth most abundant dissolved ion in seawater by both molarity and mass, after sodium, chloride, magnesium, and sulfate.
Calcium is essential for living organisms, particularly in cell physiology, where movement of the calcium ion Ca2+ into and out of the cytoplasm functions as a signal for many cellular processes. As a major material used in mineralization of bones and shells, calcium is the most abundant metal by mass in many animals.
Calcium is not naturally found in its elemental state. Calcium occurs most commonly in sedimentary rocks in the minerals calcite, dolomite and gypsum. It also occurs in igneous and metamorphic rocks chiefly in the silicate minerals: plagioclase, amphiboles, pyroxenes and garnets.

Some Applications of calsium uses are :
• as a reducing agent in the extraction of other metals, such as uranium, zirconium, and thorium.
• as a deoxidizer, desulfurizer, or decarbonizer for various ferrous and nonferrous alloys.
• as an alloying agent used in the production of aluminium, beryllium, copper, lead, and magnesium alloys.
• in the making of cements and mortars to be used in construction.
• in the making of cheese, where calcium ions influence the activity of rennin in bringing about the coagulation of milk.
There are many kinds of Calcium compounds as
• Calcium carbonate (CaCO3) used in manufacturing cement and mortar, lime, limestone (usually used in the steel industry); aids in production in the glass industry, also has chemical and optical uses as mineral specimens in toothpastes
• Calcium phosphate (Ca3(PO4)2) is used as a supplement for animal feed, fertilizer, in commercial production for dough and yeast products, in the manufacture of glass, and in dental products.
• Calcium sulfate (CaSO4•2H2O) is used as common blackboard chalk, as well as, in its hemihydrate form being more well known as Plaster of Paris.
Calcium carbonate (CaCO3) is one of the common compounds of calcium. It is heated to form quicklime (CaO), which is then added to water (H2O).
When water percolates through limestone or other soluble carbonate rocks, it partially dissolves the rock and causes cave formation and characteristic stalactites and stalagmites and also forms hard water. Read More

What is Mining ?

Mining is the extraction of valuable minerals or other geological materials from the earth, usually from an ore body, vein or (coal) seam. Materials recovered by mining include base metals, precious metals, iron, uranium, coal, diamonds, limestone, oil shale, rock salt and potash. Any material that cannot be grown through agricultural processes, or created artificially in a laboratory or factory, is usually mined. Mining in a wider sense comprises extraction of any non-renewable resource (e.g., petroleum, natural gas, or even water).

Mining of stone and metal has been done since pre-historic times. Modern mining processes involve prospecting for ore bodies, analysis of the profit potential of a proposed mine, extraction of the desired materials and finally reclamation of the land to prepare it for other uses once the mine is closed. The nature of mining processes creates a potential negative impact on the environment both during the mining operations and for years after the mine is closed. This impact has led to most of the world's nations adopting regulations to moderate the negative effects of mining operations. Safety has long been a concern as well, though modern practices have improved safety in mines significantly. Mining today is able to profitably and safely recover minerals with little negative impact to the environment.

Steps of mine development

The process of mining from discovery of an ore body through extraction of minerals and finally to returning the land to its natural state consists of several distinct steps. The first is discovery of the ore body, which is carried out through prospecting or exploration to find and then define the extent, location and value of the ore body. This leads to a mathematical resource estimation to estimate the size and grade of the deposit. This estimation is used to conduct a pre-feasibility study to determine the theoretical economics of the ore deposit. This identifies, early on, whether further investment in estimation and engineering studies is warranted and identifies key risks and areas for further work. The next step is to conduct a feasibility study to evaluate the financial viability, technical and financial risks and robustness of the project. This is when the mining company makes the decision to develop the mine or to walk away from the project. This includes mine planning to evaluate the economically recoverable portion of the deposit, the metallurgy and ore recoverability, marketability and payability of the ore concentrates, engineering concerns, milling and infrastructure costs, finance and equity requirements and an analysis of the proposed mine from the initial excavation all the way through to reclamation. Once the analysis determines a given ore body is worth recovering, development begins to create access to the ore body. The mine buildings and processing plants are built and any necessary equipment is obtained. The operation of the mine to recover the ore begins and continues as long as the company operating the mine finds it economical to do so. Once all the ore that the mine can produce profitably is recovered, reclamation begins to make the land used by the mine suitable for future use.

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Feldspar

Felspar

Felspar adalah nama kelompok mineral yang terdiri atas potasium, sodium dan kalsium alumino silikat. Pada umumnya kelompok ini terbentuk oleh proses pneumatolitis dan hidrotermal yang membentuk urat pegmatit. Felspar ditemukan pada batuan beku, batuan erupasi dan metamorfosa, baik bersifat asam maupun basa.

Bersasarkan keterdapatannya endapan felspar dapat dikelompokkan menjadi tiga jenis, yaitu endapan felspar primer, diagenetik, aluvial. Felspar primer terdapat dalam batuan granitis, felspar diagenetik terdapat dalam batuan sedimen piroklastik, sedangkan felspar aluvial terdapat dalam batuan yang telah emngalami metamorfosa. Felspar yang mempunyai nilai ekonomis yang baik adalah felspar yang berasal dari batuan asam.

Secara mineralogi felspar dapat dikelompokkan menjadi 2 kelompok mineral yaitu alkali felspar dam plagioklas. Felspar mempunyai nilai kekesaran 6 – 6,5 skala Mosh, berat jenis 2,4 – 2,8, warna dari putih keabu-abuan, merah jambu, coklat, kuning dan hijau.

Felspar adalah mineral alumina anhidrat silikat yang berasosiasi dengan unsur Kalium (K), Natrium (Na) dan Calsium (Ca) dalam perbandingan yang beragam. Mutu felspar ditentukan oleh kandungan oksida kimia K₂O dan Na₂O yang relatif tinggi diatas 6%, oksida Fe₂O₃ dan TiO_2.

Felspar digunakan di berbagai industri, sebagai bahan pelebur/perekat pada suhu tinggi, pembuatan keramik halus seperti barang pecah belah, saniter, isolasi dan industri gelas/kaca.

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