1. Tenor, Grade and specifications - Prof. GRSK

2. Important terms 2 Ore A naturally occurring mineral or rock from which a valuable or useful substance, especially a metal, can be extracted at a reasonable cost Tenor Tenor of ore is the lowest permissible metallic deposit in an ore. Any ore must contain some percentage of a metal in it. Grade The grade of ore refers to the concentration of the desired material it contains. The value of the metals or minerals an ore contains must be weighed against the cost of extraction to determine whether it is of sufficiently high grade to be worth mining.

3. Important terms cont… 3 Cut-off grade Cut-Off grade is the minimum grade required in order to mine a mineral or metal economically. Material found to be above this grade is considered to be ore, while material below this grade is considered to be waste. Specification standards and specifications relating to metallic and nonmetallic minerals and manufactures (industrial aspect) thereof. Tonnage Tonnage refers to the quantity of ore contained within an ore body or the rate at which ore is extracted from the earth.

4. Important terms cont… 4 Tonnage Factor (TF) Tonnage estimates are derived from those of volume by applying a specific gravity or tonnage or bulk density factor. A more accurate tonnage factor may be determined by actually weighing the ore from measured volumes of excavation and averaging the results. Example: Rule for tonnage estimation of ore body Length X Width = Area Area X Depth= Volume Volume X TF= Tonnage Strike Length x Width x Depth x Specific Gravity = “X” (in tonnes) 500 x 50 x 100 x 2.5 = 62,50,000 tonnes.

5. Tenor  The word tenor was used to mean metal content in an ore. But its scope enlarged to non metallic minerals also.  For example, in case of asbestos the tenor is 6%. It means that the occurrence of asbestos fiber in the ore is 6%.  While metallic deposits, such as copper ore, it is referred to as 2%, it means that the ore contains 2% copper metal.  The tenor may reach up to 100% in the case of native deposits. 5

6. Grade Example : Magnesite is marketed with following grades 6 The grade broadly signifies the commercial classification of ore based on its chemical, physical properties (or by both), sizes, etc. Also, the quality of deposit determined in terms of metal content. Incase of metallic deposits like iron ore, manganese ore, base metals, etc.

7. Commercial Grades of asbestos Group No. 1: No. 1 crude (cross fiber veins having ¾-inch staple and longer). Group No. 2: No. 2 crude (cross fiber veins having ⅜-inch staple up to ¾-inches; run-of- mine crude consists of unsorted crudes; sundry crudes consist of crudes other than above specified. Group No. 3 (commonly referred to as textile or shipping fibers) 7

8. Industrial specification 8 Industrial specification intimately related with the grade. Specification indicates the tolerance limits of all constituents presented in an ore. Individual consumers may prescribed different specifications for the same grade of mineral which is depend upon two factors: i. The technique of manufacturing process adopted by the individual unit. ii. The grade of other raw material required to be used, necessary to obtain the end product.

9. Iron Ore Specification FinesGuaranteed (%) Typical (%) Fe57 Min57.3 SiO 2 5.8 Max5.3 Al 2 O 3 4.9 Max4.5 Moist14 Max12 P0.07 Max0.05 S0.04 Max0.02 +10mm10 Max8 LOI7 About6 LumpsGuaranteed (%) Typical (%) Fe57 Min57.3 SiO 2 4 Max3.7 Al 2 O 3 5.5 Max5 Moist12 Max10 P0.08 Max0.05 S0.04 Max0.02 +40mm5 Max2 LOI7 About6 Fine vs. Lumps 9

10. Mica specification Silicon bonded muscovite mica plates-rigid Uses  Parts for hair dryers,  electric Iron,  electric stove,  electric toasters,  industrial furnaces,  offee machines,  electric rice cooker,  electric room heaters, etc. Item Rigid mica sheet MicaMuscovite Mica content %>90 Bond content %<10 Density g/cm 3 1.7~2.15 Heat Resistance Continuous service °C500 Intermittent service °C700 Flexural strength N/mm 2 >200 Water absorption %<1.5 Dielectric strength KV/mm>20 Insulation resistance23°C ohm.cm>10 17 500°C ohm.cm >10 Heat lossat 500°C %<1 at 700°C% N/M 10

11. Industrial specification of bauxite

12. In summary