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Halite is the mineral name for the substance known as rock salt and is chemical name is Sodium Chloride (NaCl) [Cornelius (1985)]. It is found in solid masses and as a dissolved solution in the oceans and in salt lakes. Rock composed primarily of halite is known as rock salt. The inland lakes that are rich in salt exist in acid region and may also be below sea level without an cutlet. These lakes evaporate during dry season causing a recession in the water level and an increase of salinity content. When this happen, salt forms on the evaporated shores of lake and also happen as the tributaries of salt lakes are diverted for human and agricultural use, causing the lakes to dry up with additional salt forming at the evaporating shore line. Many of these inkind lakes have already dried up, leaving over enormous salt deposit which may be commercially mined [Anthony et’al (1997)]
Halite also exist in non-acid region in underground deposit which can reach great depths [Hurlbut et’al (1985)]. Underground halite deposit are often mined by drilling wells into the salt layer and banging in hot water which quickly dissolves the salt into a brine. The brine is saturated with dissolved salt and is then pumped out. Halite also form from evaporation at salts spring where saline water comes out of the ground in a short salt deposit and precipitates as rounded globular masses [Lai et’al (2013)]
- OCCURRENCE OF HALITE
Halite occurs in vast bed of sedimentary evaporate minerals [Anthony et’al(1997)] that result from the drying up of enclosed laker, play as and seas [Kurlansky (2003)]. Salt beds may be hundreds of meters thick and underline broad areas. In the united kingdom there are three mines; the largest of these is at Winsford in chishire producing on average a million times per year.
Examples of compound that adopt a halite crystal structures include: MgO, CaO, MnO, FeO, NaCl, CaS, AgF, BaTe, BaSe, CaSe, SiO, LiF, MgO, SnAs, MgS, etc.
Calcium Sulphide is an inorganic compound with the formula CaS. It is a white crystaline material but often encountered in an impure form that is brown and non crystalline powder. It is generated industrially in the production of metallic iron. Calcium Sulphide is a rare non terrestial mineral miningerite detected in some meteorites. Calcium Sulphide is also found in the circumstellar envelopes of certain evolved carbon stars [Goebel (1985)].
1.2 USES OF HALITE
Halite has many uses in which most of the salt produced is crushed and used in the winter on roads to control the accumulation of snow and ice. It is an essential nutrient for humans and most animal. It is also a favorite seasoning for many types of food, significantly amount of salt are used by the chemical industry. It is also a mineral that everyone knows and a favorite seasoning in cooking [Bitterman and Mark (2010)]. It is also used as food preservation. It is also used for Sodium ore [Irons et’al (1981)]
1.3 FORMATION OF HALITE
Halite is mainly a sedimentary mineral that usually forms in acid climates where ocean water evaporates. However, many inland lakes such as the great salt lake of North America and the dead sea between Jordan and Israel are also location where halite is forming today. Halite form isometric crystals [Anthony et’al (1997)].
1.4 CALCIUM SULPHIDE
Calcium Sulphide is the chemical clompound with the formula (CaS). This white material crystallizes in cubes like rock salt. Cas has been studied as a compound in a process. The world recycle gypsum, a product of the gas desalyrization [Bradford et.al (2000)] . Like many salts containing sulfide ions, CaS typically has an odur of H2S, which results from small amount of this gas formed by hydrolysis of the salt (Lai et; al (2013) .
In terms of its atomic structure, CaS crystallizes in the same motif as Sodium Chloride indicating that the bonding in the materials is highly ionic. The high melting point is also consistant with its description as an ionic solid. In the cystal, each S2– ions surrounded by an octahedron of six Ca2+ ions and complementarily, each Ca2+ ion surrounded by six S2-ions .
1.5 OCCURRENCE OF CALCIUM SULPHIDE (CaS)
Oldhamite is the name for miuneralogical from of CaS. It is a rare component of some moleorites and has scientific importance in Sola nebula research. Burning of coal dumps can also produce the compound (Goebel (1985).
1.6 PREPARATION OF CALCIUM SULPHIDE
CaS is produced by “Carbo-Thermic reduction” of calcium sulfate, which entails the conversation of carbon usually as charcoal to carbondioxide
CaSo4 + 2C àCaS+ 2Co2
And can react further
3CaSo4 + 2CaS à4CaO + 4So2
In the second reation the sulfate (+6 Oxidation State) Oxidize the sulfide (-2 Oxidation State) to Sulfur dioxide (+4 Oxidation State). while it is being reduced to sulfur dioxide itself (+4 Oxidation State).
CaS is also a byproduct in the Leblanc process.
1.7 USES OF CALCIUM SULFIDE (CaS)
Calcium Sulfide is used as a depilatory in the tanning industry.
Calcium Sulfide is also used is cosmetic and in finely divided form.
Calcium Sulfide employed in luminous paints.
Calcium Sulfide is used in from copathy.
1.8 AIMS OF STUDY
The aims of the study is to determine the electronic properties of Calcium Sulfide using first principle method.
OBJECTIVES OF THE STUDY
The objective of the study is to determine the following calculation of electronic properties such as;
- Crystal structure
- Band Structure (Conductor, Semi-Conductor or Insulator)
- Charge density (Number of Charge per unit M)
- Density of state.
The knowledge of Calcium sulphide (CaS) will give an insight to the property of all other halite.