1. Mining And its environmental impact

2. Outline • 1. Types of Mining (and why we use them) • 2. Beneficiation • 3. Smelting • 4. Environmental Concerns of 1 through 3

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

4. Depth and Size Shallow, near surface: usually surface mining Deep, small but rich: usually underground

5. Shape of Ore Body

6. Versus

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

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

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

10. Strip Mining of Coal Kansas Geological Survey

11. Open Pit Mining

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

16. ?Dinky Toy?

17. Drilling in pit

18. Crushing in pit

19. Loading ore in pit

20. Underground Mining

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

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

26. Room and Pillar

27. Cut and Fill

28. Long Wall

29. Shrinkage Stoping

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

31. Solution Mining

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

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

38. 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

39. Sudbury Super Stack

40. Iron smelting • Blast Furnace • 3CO + Fe2O3 2 Fe + 3CO2 (gas) • 4CO+Fe3O4 3Fe + 4CO2 (gas)

41. Sulfide Minerals • Are sometimes roasted • Heated in air without melting to transform sulfides to oxides • Gives off H2S and SO2 • Then oxides processed like Fe

42. Sulfides cont’d • 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

43. Smelting

44. Result at Kidd Creek

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

47. Heap Leaching • 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. • The solutions are collected and the metals are precipitated

48. Potential Environmental Problems • A. Mining operation itself • Disposal of a large amount of rock and waste • Noise and dust • Acid Mine Drainage • Beneficiation • Dust • Tailings • Smelting and refining

49. From Underground Mining • Subsidence • Block/caving • Room and pillar

50. Subsidence from Pb-Zn mining