Preliminary Chemistry Metals Research Assignment Essay Example

Preliminary Chemistry: Metals Research Assignment Essay Ancient Egyptian map showing roads to Nubian gold mines, dated 1400-1200 BC (Located in the Egyptian Museum in Turin, Italy) Figure 1 Evidence of gold mines: Ancient Egyptian map showing roads to Nubian gold mines, dated 1400-1200 BC (Located in the Egyptian Museum in Turin, Italy) Figure 2 Ancient Egyptian hieroglyphs depicting gold Figure 2 Ancient Egyptian hieroglyphs depicting gold i) Gold was no doubt one of the first metals known to primitive man.The metal gold was first discovered by the ancient Egyptians, some 5000 years ago. The Egyptians associated metal with the sun and believed the gold to be divine and indestructible. They believed the skin of their gods was golden and the Pharaoh was called â€Å"the Golden Horus†. It was believed to be the flesh of the sun god, Ra, and was, thus, considered a symbol of eternal life. It was this association with Ra and eternal life that compelled pharaohs and queens to exploit the gold in their kingdom and to accumulate it and be buried with large stores of the metal.During the earliest periods of Egyptian history, only kings were allowed to wear golden ornaments but the privilege was later extended to priests and other members of the royal court. (Creamer, 2008). Never tarnishing, gold was also used extensively in the making of statues of gods and was even used to decorate temples. The ancient Egyptians did not use gold for currency and it had no economic importance. Evidence that the ancient Egyptians had gold is in the archaeological finds of the earliest known map, The Turin Papyrus map.This map showed an early gold mining facility and a local geography of a region in Nubia. Early Egyptian hieroglyphs from as early as 2600 BC described gold as â€Å"more plentiful than dirt† and as a divine and indestructible metal, associated with the brilliance of the sun. (Azulay, 2012). i) Gold is widespread in low concentrations in all igneous rocks and has been discovered on every continent on earth. (Yabz, 2008). When gold was first discovered it was found in many forms, just like it is today. Native gold can occur as very small microscopic particles embedded in rock, often ogether with quartz or sulphite minerals. Gold in the native state is also found in the form of free flakes, grains or larger nuggets that have ended up in alluvial deposits due to eroding from rocks. Gold is a ‘transition metal’ on the periodic table of elements and is a group 11 element. It is one of the least reactive elements when solid and under standard conditions; it does not combine with oxygen or dissolve in most acids. It does not react with halogens, such as chlorine or bromine (Mazur, 2007). The element therefore occurs commonly in native form.On the periodic table of elements, gold is surrounded by other non- reactive metals such as silver and platinum. Because gold is non-reactive it was able to be discovered and mined many centuries ago. ii) Figure 3 Examples of items made from gold tha t date back to Ancient Egyptian times Figure 3 Examples of items made from gold that date back to Ancient Egyptian times Figure 2 Ancient Egyptian Pharaoh, Tutankhamen’s solid gold burial mask Figure 2 Ancient Egyptian Pharaoh, Tutankhamen’s solid gold burial mask Gold is both ductile and malleable.Ductile means it can be drawn into thin wires. Malleable means capable of being hammered into thin sheets. A piece of gold weighing only 20 grams can be hammered into a sheet that will cover more than 6 square meters. The sheet will be only 0. 00025 centimetres thick. Gold is also very soft; it reflects light and heat but conducts electricity very well (Mazur, 2007). For the ancient Egyptians, gold had many uses including, burial masks- evidence of this is in Tutankhamen’s famous solid gold mask, found in his coffin in 1922.The metal is so malleable and soft it could be hammered into thin sheet and wires, perfect for making fine jewellery and ornaments that lasted thr ough the decades. Other uses included small statues of gods used for religious ceremonies, made out of solid gold. Another use they had for gold was royal jewellery, royal artefacts and chariots. Gold leaf was created, which was paper thin, and this was used to cover the furniture and tombs of the Pharaohs and also to cover the statues of the gods. One of the special skills developed by the Egyptians was the adding of gold to glass objects.They found a way to use gold to make glass a beautiful ruby-red colour. The glass became known as gold ruby glass iii) The ancient Egyptians extracted gold by crushing, washing, and then applying heat and the result was powdered. Ancient open-cast trenches following quartz veins from the surface and shafts sinking horizontally or diagonally into the mountain sides. A number of the shafts had stone walls reinforcing the entrances or platforms at the edge to raise and lower men, boys, baskets, tools and ore. When hard gold-bearing surfaces are found they burned it with hot fire until it crumbled, they then continue working it out by hand.Softer rock which can be mined with moderate effort is crushed with a sledge. The strongest workers break quartz rock with iron hammers. In some parts of the mine, the granite surrounding the quartz crumbles under foot this means there was no need for fire setting because the rock can be splintered away. Hundreds of crushing stones made of rough blocks of basalt, granite or porphyritic granite have been found on Egyptian gold mining sites. The ore that was mined was reduced in size when brought to the surface and the pieces worth reducing more were picked out.Once the ore they need is picked out, it is put into the mill where it is grinded into fine flour like powder by four slaves. Once the ore is ground into fine powder, it is rubbed onto a broad board which is slightly inclined, while pouring water over it. When this is done, the rocks, dirt and other matter are washed away while the partic les which contain gold remain because of its weight. This is repeated a number of times until all the remains are pure gold- dust. (TMS, 2013). In ancient times, mercury was a common form of gold extraction and was used until later on in the first millennia.The metal, mercury, has been found in ancient Egyptian tombs that date back to 1500 BC and it is believed that it was used for extracting gold from its ore. Gold ore was crushed finely, when liquid mercury was added, the mercury coated just the gold. The mercury coated gold was then burned in order to evaporate the mercury and leave the pure gold. (Brooks, 2011). iv) The crystal structure for metallic gold is face centred cubic. This crystal structure contributes to golds very high ductility since the lattices are particularly suitable for allowing the movement of dislocations in the lattice.The crystal structure for metallic gold is face centred cubic. This crystal structure contributes to golds very high ductility since the lat tices are particularly suitable for allowing the movement of dislocations in the lattice. When gold nuggets weren’t found lying around in streams or deposits, the ancient Egyptians put a lot of energy into mining their gold. Gold is a non-reactive metal, it generally does not bond with other elements which means that it takes less energy to extract than other reactive metals.Still, a lot of energy was used by the Egyptians to extract the ore because of their primitive methods. The Egyptians had more gold than any other civilization of its time, this means that the Egyptians did put a lot of energy into gold mining but also from their efforts they acquired a very large amount of gold. Gold has a cubic crystalline structure and a density of 19. 32 grams per cubic centimetre. Gold is bonded with metallic bonds, the electrons in the outer shells of the metals atoms are free to move, the metallic bond is the force of attraction between these free electrons and the metal ions.Metal lic bonds are strong, this means gold maintains a regular structure and has a high melting and boiling point. (BBC, 2013). Because of gold’s strong structure, it takes a lot of energy to break down into its pure form, just like the Egyptians discovered. But gold does not react with other elements so quite often it is found already in its pure form, which then requires little or no energy to refine. 2. Aluminium Growth of aluminium production Growth of aluminium production i) The metal Aluminium was first discovered and its existence established in 1808 by Sir Humphrey Davy, but he was unable to actually make any. 0 years later a French scientist discovered hard, red clay containing over 50% aluminium oxide. It was named bauxite, aluminium’s most common ore. (Davyson, 2002). After it was discovered it took many years of deliberate research to find an efficient method to extract the metal from its ore and even longer to create a production process that would allow the me tal to become commercially practical (Unknown, 2008). In 1825 a small lump of aluminium metal was produced for the first time, then in 1827 another scientist was able to isolate aluminium as a powder in 1827, in a process nvolving potassium and anhydrous aluminium chloride. It wasn’t until 1854 that the first method for commercial production was invented. At this time aluminium was more expensive than gold, and at one stage a bar of aluminium was exhibited at the Paris exhibition in 1855. In the next ten years, its value fell by over 90% because of new found ways of extracting it. In 1900, 8 thousand tonnes were produced, in 1964 the output was 681 thousand tonnes and in 1999 about 7 million tonnes of recycled aluminium was produced, adding to 31 million tonnes in total. i) An example of some bauxite An example of some bauxite Aluminium is the third most common element of the Earth’s crust and the most abundant metal. Because of aluminium’s high attraction to bo nd with oxygen it is not found naturally occurring in its elemental state, but only in combined forms such as oxides or silicates. It’s most common form is bauxite, an ore that is a hard, red clay containing over 50% aluminium oxide. Aluminium is found in the post-transition metals group on the periodic table of elements with symbol Al and atomic number 13.It is silvery white, and it is not soluble in water under normal circumstances. (Wikipedia, 2013). Aluminium is found in this state naturally because it is very reactive, this is shown on the periodic table of elements because of its position. Aluminium is positioned in the transition metals group, which means that it is with other metals that have some characteristics of transition metals. They are generally softer and do not conduct electricity as effectively and have a lower boiling and melting point than that of the transition metals.This is why aluminium is never found in its pure elemental state, it is too reactive wi th its environment and this is shown on the periodic table of elements by its position with other reactive metals and in the post-transition group. iii) Aluminium is the second most malleable metal and very ductile. Due to its low density, aluminium is not very hard. It has a melting point of 660. 32 °C and a boiling point of 2519 °C and has high electrical conductivity. Aluminium is not very strong in its pure form. This is because of its structure, which has dislocations which make it ductile, and malleable.When strength is more important other metals are added to make the crystal structure stronger, this makes it harder for atoms to move past each other. To preserve aluminium’s low density and light weight other elements are added to the metal to reinforce dislocations, this reduces malleability but increases its strength. By doing this, some aluminium alloys can be as strong as steel. Adding different elements achieves slightly different effects but almost all alloys are stronger than just pure aluminium. Adding copper to aluminium increases its strength, hardness and also makes it heat treatable.Manganese is often added to aluminium to increase strength and resistance to corrosion. The addition of silicon lowers the melting point and improves castability, and alloys with zinc have increased strength and hardness. What makes these alloys so distinctive is that they retain the lightweight A dislocation is pinned by a different element in an alloy, increasing strength A dislocation is pinned by a different element in an alloy, increasing strength property of aluminium whilst adding the extra properties that aluminium does not have.Because of its properties, aluminium and its alloys are used excessively in modern life. One of the most common uses for aluminium is packaging such as drink cans, foil wrappings, bottle tops and foil containers. It is perfect for packaging because of its malleability, resistance to corrosion, its impermeableness and doe sn’t let the aroma or taste out of food. Because aluminium is so light weight, that when it is made into an alloy to make it stronger it is perfect for the transport industry. A vehicle made with aluminium takes a lot less energy to move than if it was made with iron or steel.Vehicles made out of aluminium include, aeroplanes, trains, boats and cars. Aluminium is also used for power lines because is it so light and can conduct electricity over long distances without needing heavy duty supports. Its ductility is also useful in drawing it out into wires to make power lines. Buildings made with aluminium are almost maintenance free because of its corrosion resistance, this and its lightweight makes it perfect for cladding, windows, skylights, gutters, door frames and roofing.Aluminium also has many other miscellaneous uses including saucepans, kitchen utensils, golf clubs, tennis rackets, furniture, fridges and toasters (Davyson, 2002). iv) An edge dislocation leads to a pressur e field (hydrostatic tension). The incorporation of the larger magnesium atom reduces such dilatational fields and reduces the total energy of the system (Macmillan, 2010). An edge dislocation leads to a pressure field (hydrostatic tension). The incorporation of the larger magnesium atom reduces such dilatational fields and reduces the total energy of the system (Macmillan, 2010).Aluminium in its pure form is very weak. Aluminium is more commonly found alloyed with other metals for this reason; to make it stronger and keep its low density and light weight. Other metals are added which hold down dislocations, this reduces the metals ductility but increases its strength. By this method some aluminium alloys can be as strong as steel, but all the while keeping the original light weight of the aluminium. Adding different elements achieves slightly different effects, but almost all alloys are stronger than the aluminium by itself.Copper added to aluminium increases its strength and hardn ess and also makes it heat treatable. Adding magnesium to aluminium causes increased tensile strength, resistance to salt water corrosion and ease of welding. Manganese is often added to increase strength and resistance to corrosion, adding silicon lowers the melting point and improves castability and alloys with zinc also have increased strength and hardness. The properties these alloys give to the metal enhance the use of aluminium greatly. Most uses for aluminium are when it is alloyed, rather than in its pure state.These alloys make aluminium suitable for use in cars, aeroplanes, cars, trains and buildings because aluminium in its pure state simply isn’t strong enough. (Davyson, 2002) v) The Hall Heroult Process- the extraction of the aluminium metal The Hall Heroult Process- the extraction of the aluminium metal Bayer process on industrial scale Bayer process on industrial scale The first step in extracting aluminium is to remove it from the earth in mining, this is simp le because the element is so abundant. Because of its reactivity, aluminium is never found isolated in the earth, it is always found bound together with other elements in compounds.The bauxite then has to be purified using the Bayer process. This process occurs in two main steps. First the aluminium ore is mixed with sodium hydroxide in which the oxides of aluminium and silicon will dissolve, but other impurities will not. These impurities can then be removed by filtration. Carbon dioxide gas is then bubbled through the remaining solution, which forms weak carbonic acid, neutralising the solution and causing the aluminium oxide to precipitate while leaving the silicon impurities in the solution.After filtration, and boiling to remove water, purified aluminium oxide can be collected. Once purified aluminium oxide has been manufacture, aluminium can be removed from it using the Hall-Heroult method. The aluminium oxide is mixed with cryolite (mixture of sodium fluoride and aluminium fl uoride) then heated to 980? C to melt the solids. This is much a much lower temperature than required to melt aluminium oxide so much energy is saved. The molten mixture is then electrolysed with a large current and the aluminium ions are reduced to form aluminium metal. i) The process for extracting pure aluminium metal takes a long time and a huge amount of energy. The process in the extraction of the aluminium that takes the most energy is the electrolysis to reduce the ions to form metal. The aluminium oxide mixed with cryolite has a melting point of 950 degrees Celsius, which on such a large scales takes an obscene amount of energy. (Williams, Unknown). Electric power represents about 20% to 40% of the cost of producing aluminium, depending on the location of the smelter.Aluminium production consumes roughly 5% of electricity generated in the U. S. (Wikipedia, 2013). Aluminium is so hard to extract from aluminium oxide and takes so much energy because of the covalent bonding. A luminium oxide is bonded covalently, which means that all the elements are connected very strongly and are hard to break apart, hence the reason why it takes so much time and energy to extract pre aluminium. Structure of pure aluminium Structure of pure aluminium 3. Copper i) Copper is mainly found in porphyry copper deposits, which are the largest source of copper ore.These porphyry deposits, which generally contain a mixture of igneous rocks such as feldspar, copper and quartz appear as a purple-red stone. These deposits are formed when a column of rising magma is cooled slowly deep into the crust, creating large crystal grains, with a diameter of 2 mm or more. In the final stage, the magma is cooled rapidly at relatively shallow depth or as it erupts from a volcano, creating small grains that are usually invisible to the naked eye. These deposits have multiple cavities of diorite to quartz.It is also found mixed in with rock composed of broken, rounded fragments of minerals and o ther rocks, sulphide mineralization often occurs between or within fragments. The deposits typically have an outer calcium aluminium iron (epidote) layer. (Wikipedia, Porphyry copper deposit, 2013). ii) The most common ores are known as sulphide ores in which the copper is chemically bonded with sulphur. The other ores are oxide ores, carbonate ores, or mixed ores depending on the chemicals present. Many copper ores also contain significant quantities of gold, silver, nickel and other valuable metals.Common ores of copper are in the following list Name| Formula| Chalcopyrite (copper iron sulphide)| CuFeS2| Chalcocite (copper sulphide)| Cu2S| Covellite (copper sulphide)| CuS| Bornite (copper iron sulphide)| Cu5FeS4| Tetrahedrite (copper antimony sulfosalt)| Cu3SbS3  + x(Fe,Zn)6Sb2S9| Malachite (copper carbonate hydroxide)| Cu2CO3(OH)2| Azurite (copper carbonate)| Cu3(CO3)2(OH)2| Cuprite (copper oxide)| Cu2O| Chrysocolla (copper silicate)| CuO†¢SiO2†¢2H2O| iii) Predicting yield is a very important step when it comes to mining and extracting copper in commercial ore deposits.This is because mining copper is a huge job, and it is vital to know that the amount of copper mined will supersede the cost of mining the copper. Mining procedures such as drilling, explosive blasting, power shovels and smelting cost a lot of money and take a lot of time. Copper excavating pits may grow to be a mile or long or even longer, this is why the amount of copper that is available to be yielded needs to be predicted, so that they know their efforts will not go to waste. It also reduces the amount of excavating pits needed and reduces the energy consumed. v) The most common copper ore is chalcopyrite, it makes up around 50% of copper production. To extract this as a pure metal, the ore must be process in a specific way. Firstly the ore that has been mined is crushed up into small pieces, these pieces are then ground in a ball mill, a round cylinder containing large metal ball which rotates to grind the ore into fine powder. The sulphide ore is then mixed with xanthate reactants (alcohol and hydroxide) in an aeration tank filled with water. These two react and the copper sulphide becomes hydrophobic on the outside.When air is pumped through the tank the copper sulphide is repelled from the water and attaches itself to the air bubbles. As the air rises to the surface of the water, the copper sulphide is carried with it and separated from the rest of the composition of the ore, which is normally discarded as tailings. This method is called froth floatation. In this way copper is concentrated and purified to contain a higher proportion of copper metal, the product of the froth floatation is about 30% copper. From here the copper sulphide is then subjected to smelting.The material is mixed with silica and limestone and then smelted at 1200 °C. This chemically removes the copper from any other elements which is bound to it. The remaining waste product i s called slag and is either disposed of or refined to further remove copper. The liquid copper that is then produced is called copper matte, this product contains around 70% copper in the form of copper sulphide and iron sulphide. In order to remove the sulphur from the matte, oxygen is blown through the molten mixture and combines with the sulphur to produce sulphur dioxide: Cu2S+3O2= 2Cu2O+2SO2 The end product contains close to 98% copper and is commonly called a blister because of the cracks on its surface due to the sulphur dioxide escaping. From the blister, anodes are made and these are immersed into an acid bath. The process of electrolysis creates cathodes of high concentration copper as the ions are attracted to a sheet of pure copper foil. This copper has a concentration of around 99. 9% and the copper is then converted into its various forms, such as slabs and wires. Ablett, 2013) A disadvantage to this method is that it uses a lot of energy, but it is still used because a better method has not been invented and copper is so valuable. Energy considerations include the high temperatures necessary for smelting and energy to run machines to refine and excavate. (Clark, 2005). vii) Copper prices change due to a number of variables. One of the main reasons is the demand for the metal and how much there is and also the quality of the copper for sale.Recycled copper is actually more valued than the raw product, this is because premium grade scrap undergoes less cleansing processing than newly mined copper, making it a purer form. If there is a large amount of copper in demand but the supply is low, copper prices are bound to be high, on the other hand, when demand it relatively low with an excess supply of copper ore, then copper prices will be low as well. (Prices, 2012). Copper is reasonably expensive as shown in the tables below, this is due to the involved extracting and refining process and the abundance. Bibliography Ablett, E. 2013). The Extraction of Copper. Retrieved from Metal Assignment: http://metalsassignment. wikispaces. com/The+Extraction+of+Copper Azulay, T. (2012). A History of Gold: the Ancient World. Retrieved from Tal Azulay Jewellery : http://talazulay. com/dynamic/articles/about/A%20History%20of%20Gold%20-%20the%20Ancient%20World/index. htm BBC. (2013). Different substances and their properties. Retrieved from BBC: http://www. bbc. co. uk/schools/gcsebitesize/science/add_aqa_pre_2011/atomic/differentsubrev5. shtml Brooks, W. E. (2011). Amalgamation and small-scale gold mining . Retrieved from IFEA: