1. Mining And its environmental impact

2. What determines the type of mining? Underground v.s. Surface Mining v.s. Solution Underground v.s. Surface Mining v.s. Solution –Depth of below surface –Size of the ore body –Shape of the ore body –Grade –Type of Ore

3. Depth and Size

4. Shape of Ore Body

5. versus

6. Type of Ore Is the ore mineral soluble in water? Is the ore mineral soluble in water? Can the ore be melted? Can the ore be melted?

7. What are the types of mining? Surface Surface –Strip –Open Pit –Placers--Dredging Underground Underground Solution Solution

8. When do you use Surface Mining? Large tonnage Large tonnage High rates of production High rates of production Overburden (including rock) is thin Overburden (including rock) is thin

9. Strip Mining of Coal Kansas Geological Survey

10. Open Pit Mining

13. Some photos and machinery used in open-pit mining

15. ?Dinky Toy?

16. Drilling in pit

17. Crushing in pit

18. Loading ore in pit

19. Underground Mining

20. When do we mine underground? The ore deposit is deep The ore deposit is deep Ore body is steep Ore body is steep Grade is high enough to cover costs Grade is high enough to cover costs

22. Some types of underground mining Room and Pillar Room and Pillar Cut and Fill Cut and Fill Long wall (coal) Long wall (coal) Shrinkage Stoping Shrinkage Stoping Block Caving Block Caving

23. Room and Pillar

24. Cut and Fill

25. Long Wall

26. Shrinkage Stoping

27. Block Caving www.ivanhoe-mines.com/s/Mongolia_ImageGallery

28. Solution Mining

29. Beneficiation Means of separation of ore mineral from waste material (or gangue minerals) Also known as Liberation

30. What does it entail? Crushing and Grinding Crushing and Grinding –Ball mill or rod mill Separation Separation –Density (e.g. diamonds with a jig) –Magnetic properties –Electric properties –Surface properties

35. Refining the Ore Smelting removes the metal from the ore mineral by a variety of ways Heap Leaching removes metal from the ore by solution removes metal from the ore by solution

36. Iron in review Blast Furnace Blast Furnace 3CO + Fe 2 O 3 2 Fe + 3CO 2 (gas) 3CO + Fe 2 O 3 2 Fe + 3CO 2 (gas) 4CO + Fe 3 O 4 3Fe + 4CO 2 (gas) 4CO + Fe 3 O 4 3Fe + 4CO 2 (gas)

37. Sulphide Minerals Are sometimes roasted Are sometimes roasted –Heated in air without melting to transform sulphides to oxides –Gives off H 2 S and SO 2 –Then oxides processed like Fe

38. Sulphides cont’d Process of roasting and smelting together creates a matte Process of roasting and smelting together creates a matte –Sulfides are melted into a matte and air is blown through. S is converted to sulfur dioxide and Fe to iron oxide, and Cu and Ni stay in melt

39. Smelting

40. Result at Kidd Creek

41. Sulphides cont’d Solvent extraction/electroplating Solvent extraction/electroplating –Used where rock contains Cu but in too little amounts to be recovered by classical methods

43. Heap Leaching In this process, typically done for Au, the ore is not ground, but rather, crushed and piled on the surface. In this process, typically done for Au, the ore is not ground, but rather, crushed and piled on the surface. Weak solutions of NaCN (0.05%) percolate through the material leaching out the desired metals. Weak solutions of NaCN (0.05%) percolate through the material leaching out the desired metals. The solutions are collected and the metals are precipitated The solutions are collected and the metals are precipitated

44. Potential Environmental Problems A. Mining operation itself A. Mining operation itself –Disposal of a large amount of rock and waste –Noise –Dust Beneficiation Beneficiation Smelting and refining Smelting and refining

45. From Underground Mining Subsidence Subsidence –Block/caving –Room and pillar –Salt mining (Droitwich)

46. Subsidence in rancher’s field

47. Subsidence from Pb-Zn mining

48. From Underground Acid Mine Drainage Acid Mine Drainage –FeS minerals in coal –Sulphide deposits –Acidic streams can pick up heavy elements and transport them

49. Rock that has acid forming material

50. Drainage

51. Acid and open pits Berkley Pit

53. Other problems with open pits Very large holes Very large holes Pit slopes steep and not stable. Cannot be maintained Pit slopes steep and not stable. Cannot be maintained May fill with water May fill with water Strip coal mines –loss of top soil in past Strip coal mines –loss of top soil in past –Now smoothed out and top soil added

54. Disposal of Waste Rock More problematic for open pit than underground More problematic for open pit than underground Waste rock piles have steep angle of repose and thus may not be stable Waste rock piles have steep angle of repose and thus may not be stable Bingham in its hay day produced 400,000 tons of waste rock per DAY! Bingham in its hay day produced 400,000 tons of waste rock per DAY!

55. Tailings ponds From concentrating usually have high pH From concentrating usually have high pH –At Bingham acid waters mixed with tailings water to neutralize Different metals have different problems Different metals have different problems

56. Problems with Smelting/Roasting Air: SO 2 and CO 2 and particulate matter Air: SO 2 and CO 2 and particulate matter Noranda Quebec used to have the highest single point source of SO 2 in the world. It may have been surpassed. Noranda Quebec used to have the highest single point source of SO 2 in the world. It may have been surpassed. CN (Au); NaOH and F (Al); solvents (electrotwinning); heavy metals; oil and grease CN (Au); NaOH and F (Al); solvents (electrotwinning); heavy metals; oil and grease