Impact On Environment

Results on Impact on Environment:





Land:
Rehabilation of land is important as the land or extraction is near to the natives and it is our responsibility to restore back to original after using their land. This is also been done to prevent erosion from occuring in the land.

Biodiversity:
Impact on the natural environment including the diversity of flora, fauna and their habitats.

Solution: To minimise destruction of the natural habitat, BHP try to choose places with lesser diversity. But if they had to mine areas with diversity, they will cautiously moved the entire habitat to other areas and back to the original when they are done.

Air emissions:
Air pollution always happen.

Solution: Even though emitted air from mining is safe when it is in a remote place and will not damage the air quality, mine workers still have to wear mask as they are the nearest to the gases.

Waste:
Throuh BHP's different activities, their sites generate a variety of wastes,in the form of general and hazardous waste.

Solution: General and hazardous waste is accepted at normal landfills or waste incinerators including papers, timber and domestic wastes. Hazardous waste such as oil, chemical wastes and baghouse dust are not accepted at normal lanfills. The national legislation will decide whether the waste is hazardous or non-hazardous.

-E.g. the slag from our iron in Australia is classified as hazardous waste.

(source from: www.bookrags.com/essay-2003/12/5/35456/6404)

Iron Extraction Method

Metal on Research: Iron
Extracting iron from iron ore using a Blast Furnace





90% of all mining of metallic ores is for the extraction of iron. Industrially, iron is produced starting from iron ores, principally hematite and magnetite by a carbothermic reaction in a blast furnace at temperatures of about 2000 °C.

In a blast furnace, iron ore, carbon in the form of coke, and a flux such as limestone are fed into the top of the furnace, while a blast of heated air is forced into the furnace at the bottom.

In the furnace, the coke reacts with oxygen in the air blast to produce carbon monoxide:
*********************************************

2 C + O2 → 2 CO
The carbon monoxide reduces the iron ore to molten iron, becoming carbon dioxide in the process:

3 CO + Fe2O3 → 2 Fe + 3 CO2
The flux is present to melt impurities in the ore, principally silicon dioxide sand and other silicates. Common fluxes include limestone and dolomite. Other fluxes may be used depending on the impurities that need to be removed from the ore. In the heat of the furnace the limestone flux decomposes to calcium oxide:

CaCO3 → CaO + CO2
Then calcium oxide combines with silicon dioxide to form a slag.

CaO + SiO2 → CaSiO3
The slag melts in the heat of the furnace. In the bottom of the furnace, the molten slag floats on top of the denser molten iron, and apertures in the side of the furnace are opened to run off the iron and the slag separately. The iron once cooled, is called pig iron, while the slag can be used as a material in road construction or to improve mineral-poor soils for agriculture.

(Source from: http://en.wikipedia.org/wiki/Extraction_of_iron#Blast_furnace)

How Iron was extracted in the 19th century:


(Source from: http://en.wikipedia.org/wiki/File:Iron-Making.jpg)

EXPERIMENT!!!!!
Iron extraction-match head & reaction releasing CO2

General overview of the different methods of Extraction of Metals

Types of extraction


Many metals are found in the Earth's crust as ores. An ore is usually a compound of the metal mixed with impurities. When the metal is dug up, a method must be used to separate the metal from the rest of the ore. This is called extracting the metal.

The method of extraction depends on reactivity of the metal. The more reactive the metal, the more difficult it is to extract from its compound.

1)Electrolysis:
-Used in extracting aluminium and extracting sodium from rock salt.
-In the case of the rock salt, it is first melted in giant steel tanks.
-The extraction of aluminium is dealt with in a separate learn its within this topic.
-Electrolysis is the most powerful extraction method. But it takes a lot of electricity and that makes it expensive.

Hence, electrolysis is only used for the most reactive metals.


2)Heating with Carbon monoxide:
-Used for extracting iron from iron ore using the blast furnace.
-Cheap

Hence, heating with carbon monoxide widely used.

3)Roasting in Air:
-Used in extracting copper from copper (I) sulphide (copper pyrites).
-The copper is extracted by roasting the ore in air.

One method of Extraction of Metals is:
Iron Ore mining.


(Soure from: http://www.youtube.com/watch?v=TtA0p09SE6o&feature=related)

This blog is created by Lin Xiaoyin, Loh Huimin, Khoo Weishu, Wee Shimin and Zhang Suyi of class 3E6 for our E-learning day 2009 Chemistry Project on the topic: The Extraction of Metals and Its Impact on the Environment.

Hope you would like it :D