2 CONTENTS INTRODUCTION IMPORTANT DIAMOND PRODUCING COUNTRIES AND COMPANIES IN THE WORLD.TYPES OF DIAMOND.TYPES OF DIAMOND MININGMINERAL PROCESSING OF DIAMONDDIAMOND MINING IN INDIACONCLUSION2
3 INTRODUCTION Diamond is a transparent gem made of carbon The Diamond came from the Greek word adamas which means unconquerableDiamond forms in the kimberlite pipesThe formation of diamonds began very early in the earth's historyThe centre of the planet to become subjected to incredible extremes of temperatures and pressure.It was these conditions that caused deposits of carbon to begin to crystallise deep in the earth.3
4 As the earth's surface cooled, volcanic activity forced streams of magna (liquid rock) to the surface, carrying with it the diamond crystals.Later, the diamond-bearing rock hardened, encasing the diamonds in vertical volcanic "pipes".Subsequent erosion of the topsoils over millions of years washed some of the diamonds into streams and rivers, and sometimes as far away as the sea.The diamond is thousands of times harder than corundum, the next hardest substance from which rubies and sapphires are formed.4
5 PROPERTIES Chemistry – C Class – Native Mineral Sub class – Non MetallicGroup – carbon5
6 IMPORTANT DIAMOND PRODUCING COUNTRIES AFRICAAngola, Botswana, South africaAUSTRALIANORTH AMERICACanada, USA.ASIARussia, India.
7 TYPES OF DIAMOND PINK DIAMOND WHITE DIAMOND WHITE WITH SECONDARY PINK COLOURCHAMPAGNE DIAMONDYELLOW DIAMONDBLUE DIAMONDGREEN DIAMOND.
8 PINK DIAMONDThe pink diamond is the world's most rare and valuable diamond.The Argyle mine is the world's foremost source of unrivalled intense pink diamonds, producing 95% of the world's supply.
9 WHITE DIAMONDWhite diamonds are produced by mines all over the world in a wide variety of shapes and sizes.The white diamonds recovered from the Argyle mine are particularly brilliant and of high quality.
10 WHITE DIAMOND WITH SECONDARY PINK COLOUR. white diamond will display slight to bold flashes of pink when viewed from the top.
11 CHAMPAGNE DIAMONDSChampagne diamonds are naturally coloured diamonds that are produced in a wide range of colours from light straw to rich cognac
12 YELLOW DIAMONDFancy yellow diamonds come in a broad range of shades ranging from light yellow colour.A limited quantity of fancy yellow diamonds is recovered from the Argyle mine.
13 GREEN DIAMONDA limited quantity of fancy green diamonds is recovered from the Argyle mine.The penetration of colour is not deep.
14 BLUE DIAMONDFancy blue diamonds are available in a wide range of shades, from the blue of the sky to a more "steely" colour than sapphire.less number of this diamond is mined in argyle mines.
15 ARGYLE DIAMOND MINING Key Data Producer -- Diamonds Location -- Kimberley, northeast Western AustraliaOwnership -- Rio Tinto (100%)Geology type -- Precambrian diamond-bearing lamproite pipe with associated placer depositsMineral type -- Native diamondsReserve base -- 83Mt at 2.7ct/t hard-rock, plus 28Mt at 0.2ct/t alluvial (2005)
24 TYPES OF DIAMOND MINING ALLUVIAL MININGPIPE MINING
25 PIPE MININGPipe mining refers to the extraction of diamonds from volcanic pipes.Typically, a very large area has to be covered. An average of 250 tonnes of ore must be mined in order to produce a one-carat gem quality polished diamond.In most countries, a diamond pipe mine is composed of kimberlite, or blue ground.After the diamond-bearing rock is brought to the surface, it is then transported to a screening plant where the diamonds are separated from the hostrock.
27 ALLUVIAL MININGThis process involves the extraction of diamonds from riverbeds or ocean beaches.Millions of years ago, at the time the diamond pipes were formed, some diamonds were weathered out of the pipes and carried great distances along rivers and even into oceans.A wall is built in beach to hold back the surf.Up to 25 metres of sand is bulldozed aside to reach the diamond-bearing level.Once reached, the diamond-bearing earth is removed and transported to screening plants
29 Screening ProcessOnce a mining operation yields ore, the diamonds mustbe sorted from the other materials.This process relies primarily on diamond's high density.An old but effective method is to use a washing pan, which forces heavy minerals like diamond to the bottom and waste to the top.Cones and cyclones use swirling heavy fluids mixed withcrushed ore to achieve density separations.With this process 99% of the waste in the ore removed.
31 Further separations may use either a grease table or an x-ray separator. Final separation and sorting is done by eye.Crushed ore is mixed with a muddy water suspension, called puddle, and all is stirred by angled rotating blades in the circular washing pan.Heavier minerals settle to the bottom and are pushed toward an exit point, while lighter waste rises to the top and overflows as a separate stream of material.
32 The surface of diamond is highly unusual in that it resists being wetted by water but sticks readily to grease.Here, wet gravel washes across 3 inclined surfaces covered with beeswax and paraffin.Diamonds stick to the grease while wetted waste minerals flow past.The operator routinely scrapes the material that adheres to the table into a grease pot, using a trowel.The grease in the pot is melted and the diamonds are removed in a strainer .More automated systems use a rotating grease belt and craper.
34 Cones (left) and cyclones (right) use heavymedia separation. Diamond-bearing concentrate is mixed with a fluid near the density of diamond.Separation occurs in cones and cyclones by swirling the mixture at low and high velocities respectively.In the cone, rotational mixing permits lighter minerals to float to the top and run out as overflow, while diamonds and dense minerals sink to the bottom and are sucked out by a compressed air siphon.
35 In the cyclone, fast rotation of the suspension drives heavy minerals to the conical wall, where they sink to the bottom and are extractedThe float waste minerals are sucked from the centerof the vortex.Cyclones are about % efficient at concentrating diamonds and similarly denseMinerals from the original ore.
36 PROCESS DONE AFTER SEPARATING DIAMOND CUTTINGPOLISHINGVALUINGCLARITY GRADINGSCARAT ANALYSIS.