ME551/GEO551 Geology of Industrial Minerals Spring 2007

1. ME551/GEO551 Geology of Industrial Minerals Spring 2007 Commodities, Part 2 Clays, Diamonds, Diatomite, Fluorite, Garnet, Graphite

2. Reminders • What is trap rock? • Field trip to potash mines next week • Monday leave at 9 AM • Tues tour and return to Socorro • Hotel • Buckets for collecting • Term Projects? • March 20 I will not be teaching—Jim Barker • Any questions on the midterm? • Due March 9

3. Clays • Bentonite—Jeremy

4. Clays—Introduction • Stone age • Types • ball clay (primarily of kaolinite with illite, chlorite, smectite minerals, quartz) • bentonite (smectite with feldspars, biotite, quartz) • common clay (illite and chlorite, others) • fire clay (kaolinite, halloysite, diaspore) • fuller’s earth (attapulgite, montmorillonite) • kaolin

5. Types • layer silicates • layers of tetrahedral and octahedral sheets • Kaolinite, smectite, illite, chlorite, vermiculite • the metal oxides and hydroxides and oxy-oxides • gibsite • amorphous and allophanes • structurally disordered aluminosilicates • Allophane, Imogolite

6. Clays—definition • particle size of less than 2 micrometers • family of minerals • rock term

7. Clays—properties • chemical composition • layered structure • size • great affinity for water (double in thickness when wet) • soak up ions, release the ions later when conditions change

8. Clays—properties • Color • plasticity • mineral composition • absorption qualities • firing characteristics • clarification properties

9. Properties—charge sources • Two main sources of charge in clay minerals are isomorphous substitution and pH-dependent charges. http://jan.ucc.nau.edu/doetqp/courses/env320/lec12/Lec12.html

10. Charge properties • Charge development of on silicate clays is mainly due to isomorphous substitution. • This is the substitution of one element for another in ionic crystals with out change of the structure. • It takes place during crystallization and is not subject to change afterwards. • It takes places only between ions differing by less than about 10% to 15% in crystal radii. • In tetrahedral coordination, Al3+ for Si4+ and in octahedral coordination Mg2+, Fe2+, Fe3+ for Al3+. • Charges developed as a result of isomorphous substitution are permanent and not pH-dependent.

11. Charge properties • In allophanes, some silicate clays e.g. kaolinite, and the metal oxides the main source of charge are termed pH -dependent charges because these charges depend on the pH of the soil. • pH depend charges are variable and may either be positive or negative depending on the pH of the soil. • In the metal oxides acid soils tend to develop positive charges because of the protonation of the oh ggoud on the oxide surfaces.

12. Clay—uses • Ceramics • fillers and extenders • construction (hydraulic cement, structural clay products, aggregates) • drilling mud • fiberglass • Iron Ore Pelletizing • paper • carrier to mix paint and color pigment

13. Ball clay—uses • Burn to a light color and accepts glaze, plastic • 35% floor and wall tile • 22% sanitaryware • 43% other uses

14. Bentonite—uses • Clay consisting of smectites

15. Common clay—uses • 56% brick • 20% cement • 16% lightweight aggregate • 8% other uses (fillers and extenders)

16. Fire clay—uses • 73% refractories • 27% other uses

17. Fuller’s earth—uses • mineral substance characterized by the property of absorbing basic colors and removing them from oils • fulling of wool to remove oil and grease • 75% absorbent uses • 25% other uses

18. Kaolin—uses • Near white containing kaolinite • 55% paper • 7% refractories • 38% other uses

19. Kaolin—uses • mildew-resistant latex paints • vinyl wire insulation • printing inks • Cosmetics • rubber tires • fiberglass and nylon • auto and truck body components • production of medicines • ceramics • catalysts for petroleum refining • extenders for fertilizers, pesticides, and herbicides

20. Kaolin

21. Clays—substitutions • Limited substitutions possible • calcium carbonate • talc

22. Clays—production • ball clay • common clay: various • fire clay • fuller’s earth: U.S., Germany • kaolin: U.S., Uzbekistan, Czech Republic, United Kingdom, Brazil

23. Clays—geology • soil horizons • continental and marine sediments • geothermal fields • volcanic deposits • weathering rock formations • coal beds

24. Bricks—processing • Common clay used to make bricks • formed or shaped either by extrusion • involves forming a column of clay by pushing the material through a die at high pressure. • then cut into bricks (known as 'wirecut') • drainage pipes and clay roof tiles made similar process

25. Bricks—processing • or the 'soft-mud' process • individual bricks are formed in a sand-lined mould from a clay with a relatively high moisture content (known as 'stock' bricks) • dried prior to firing • fired using natural gas in a linear kiln known as a 'tunnel kiln’ • 1050–1100°C

26. Environmental considerations—clay • Open pits • organic emissions (EPA developing standards, MACT) • impoundment of slimes • dust control

27. Colin C. Harvey, 1999

28. Diamonds

29. Diamonds • Greek adamas meaning invincible • Used in India 2,500 yrs ago

30. Diamonds—introduction • clarity, color, shape, size is used as industrial-grade diamond (nongem) http://www.brysonburke.com/diamonds_find_the_source.html

31. Diamonds—properties • Hardest substance known • highest thermal conductivity • chemical stability • optical properties • refract light atomic connectivity of the carbon atoms gives the gem its hardness

32. Diamonds—production

33. Diamonds—uses • Middle Ages--healing powers • Grinding • drilling • cutting • polishing • abrasive • wear- and corrosion-resistant coatings, • special lenses • heat sinks in electrical circuits • wire drawing

34. Diamonds—substitutions • cubic boron nitride • silicon nitride • but diamond is more than twice as hard • synthetic diamonds (US)

35. Diamonds—geology • Kimberlites • lamprorites • alluvial (placer) deposits for these rocks • molten rock from 75 to 120 miles below the earth's surface 40 kbar and 900° C

36. The slightly misshapen octahedral shape of this rough diamond crystal in matrix is typical of the mineral. Its lustrous faces also indicate that this crystal is from a primary deposit http://en.wikipedia.org/wiki/Diamond

37. Schematic diagram of a volcanic pipe http://en.wikipedia.org/wiki/Diamond

38. Indicator minerals • ilmenite • titanium and magnesium rich chromite • chrome diopside • magnesium rich olivine • pyrope garnets • eclogitic garnets

39. Carat • carat weight measures the mass of a diamond • One carat is defined as a fifth of a gram • 200 milligrams • approximately 0.007 ounce • point unit—equal to one one-hundredth of a carat (0.01 carat, or 2 mg)

40. Price

41. Mining Alluvial mining by traditional methods continues, as seen here in Sierra Leone.

42. Mining

43. Diamonds—processing • Crush • scrubbers and degritting and sanding sections remove fine waste material for disposal • Heavy-medium separation or grease belts • X-ray fluorescence sorters are used to extract the diamonds

44. Diatomite

45. Diatomite—introduction • made of plant fossils shaped like soda straws • silica • looks like chalk (CaCO3) • diatomaceous earth

47. Diatomite http://www.rockdetective.org/f...

48. Diatomite http://www.maidenwell.com/

49. Chemical composition • 86% silica • 5% sodium • 3% magnesium • 2% iron

50. Diatomite—properties • Light weight (hollow fossil shells) • does not conduct heat