Zinc, Zinc Deposits in Pakistan

Presentation by Ahzaz Khan

& Samiullah

Zinc General Properties:

1: Zinc is a natural component of the earth’s crust.2: Symbol (Zn)3: Appearance ( Bluish pale gray )4: Zinc is present not only in rock and soil, but also in air, water and the biosphere. Plants, animals and humans contain zinc. 5: Density 7.14 g/cm36: Crystal structure Hexagonal close-packed7: Group, block Group 12, d-block8: Phase Solid9: Element category Transition Element

Zinc

Associated Metals:

Zinc is normally associated with lead and other metals including copper, gold and silver.

Zinc Minerals:

The most commonly found zinc mineral is sphalerite (ZnS) also known as zinc blende, which is found in almost all currently mined zinc deposits. The mineral crystallizes from the hydrothermal solution as purezinc sulphide.

• Other zinc containing minerals are

1: Hemimorphite Zn4Si2O7(OH)2 H2O2: Hydrozincite   Zn5(CO3)2(OH)6

3: Calamine Fe2O4Zn4: Zranklinite ZnFe2O4

5: Smithsonite ZnCO3

6: Willemite Zn2SiO4

7: Zincite ZnO

Zinc Deposits:

Zinc ore deposits are widely spread throughout the world. Zinc ores are extracted in more than 50 countries. China, Australia, Peru,US, Europe, India, Kazakhstan and Canada are the biggest zinc mining countries.

Types Of Zinc Deposits

There are four major types of zinc deposits:

1: Volcanic hosted Massive Sulphide2: Carbonate hosted ( Mississipi Valley & Irish Types)3: Sediment hosted (Sedex deposits)4: Intrusions related ( Skarn, Vein)

1: Volcanic hosted massive sulphides (VMS)

VHMS deposits are polymetallic and are an important economic source of copper and zinc often associated with significant concentrations of silver, gold , cadmium, bismuth or tin.

2: Carbonate hosted (Mississippi Valley types)

Limestone and dolomite are the most common host rocks. The zinc lead content usually ranges from 5%-10% with zinc usually predominating over lead. Concentrations of copper, silver and barite of fluorite may also be present.

3: Sediment hosted (sedex deposits)

The host rocks are mainly shale, siltstone, and sandstone. Sedex deposits represent some of the world’s largest accumulations of zinc, lead and silver. The mineral has a high silver content. The lead/zinc content ranges from 10-20%.

4: Intrusion related (high sulphidation, skarn, manto, vein)

These deposits are typically found in carbonate rocks in conjunction with magmatic-hydrothermal systems and are characterized by mineral association of calcium and magnesium. Typically the ore body contains more lead than zinc and is associated with silver

Zinc Deposits Of Pakistan

The Jurassic rocks of the Lasbela – Khuzdar Belt have the potential to host several World class' zinc – lead ore deposits. Zinc deposits are also found in Duddar , Surmai and Gunga  which are estimated over 160 million tons.

Tectonic Settings:In carbonate rocks The stratiform massive deposit found in association with

black shales, mudstones/argillaceous limestones and pyroclastic /brecciated rocks.

Rifting Environment

Form:Stratiform or layered type deposites

Age: Mesozoic (Jurassic)

Case Study ( Gunga) The Gunga deposit is located at about 3.5 km south-southeast of the

village Gunga . It is accessible from Khuzdar by traveling 11 km to the southeast on road. The distance from Khuzdar to Karachi and Khuzdar to Quetta is approximately 350 km and 270 km respectively. RCD Highway connects both the cities with Khuzdar.

The Gunga deposit is hosted by the lower part of the Early to middle Jurassic Anjira formation of the Ferozabad Group. The host rocks are predominantly black carbonaceous shale, siltstone and mudstone, subordinate limestone and local synsedimentary breccia and conglomerate.

On the basis of drill hole data, total ore reserves are estimated at 30.51 million tones of which 22.7 million tons are sulphide and the balance 7.81 million tons are oxide ores. The lead-zinc ore has a grade value of 0.66% Pb, 3% Zn.

Mining method:1: Openpit mining for shallower deposits.2: Underground mining Techniques involve creating tunnel or drift along vein. The ore is removed by drilling and blasting, and removed through the drift to the shaft

Drift: Horizontal passageway in a mine, following the bed (of coal, for instance) or vein of oreShaft: Near-vertical tunnel from the top down, where there is initially no access to the bottom

Uses Of Zinc:Zinc is used in alloys such as brass, nickel silver and

aluminium solder. Zinc oxide is widely used in the manufacture of very many

products such as paints, rubber, cosmetics, pharmaceuticals, plastics, inks, soaps, batteries, textiles and electrical equipment.

Zinc is also used Galvanizing to protect steel from corrosion.