Difference between revisions of "Adventist Youth Honors Answer Book/Nature/Rocks & Minerals - Advanced"

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(8. Discuss the content of three statements from the writings of Ellen G. White concerning rocks or mine)
(Comminution)
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{{honor_header|3|1949|Nature<br>General Conference<br>2001 Edition}}
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'''Mineral processing''', otherwise known as mineral dressing, is the practice of beneficiating valuable minerals from their [[ore]]s.
==1. Have the Rocks and Minerals Honor ==
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Industrial mineral treatment processes usually combine a number of unit operations in order to liberate and separate minerals by exploiting the differences in physical properties of the different minerals that make up an ore.
{{ay prerequisite|Nature|Rocks & Minerals}}
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==2. Have a collection of 30 rocks and minerals properly named, 20 of which you have personally collected. Label with collector's name, date and locality in which it was found. ==
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Many plants also incorporate hydrometallurgical or pyrometallurgical processes as part of an extractive metallurgical operation.  
==3. Know two minerals that belong to each of the following crystal systems:==
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===a. Isometric ===
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===b. Hexagonal ===
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===c. Tetragonal ===
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==4. Know Mohs' scale of hardness and the simplified field tests of hardness. By using these field tests, collect a scale range of specimens from your own region to form your own hardness test set. ==
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==5. Do one of the following:==
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===a. Know and tell two different processes by which metals are extracted from ores.===
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===b. Know eight minerals and tell how each is used. ===
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==6. Define the following: ==
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===a. Crystalline ===
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===b. Cryptocrystalline ===
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===c. Breccia ===
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===d. Noncrystalline ===
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===e. Fibrous fracture ===
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===f. Vitreous luster ===
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===g. Geode ===
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===h. Petrification ===
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===i. Stalactite===
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===j. Fluorescence ===
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==7. What four metals are frequently found in native or free form? ==
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==8. Discuss the content of three statements from the writings of Ellen G. White concerning rocks or minerals.==
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==References==
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Mineral processing involves four general types of operations:  '''Comminution''' or particle size reduction, '''Sizing''' or separation of particle sizes by screening or classification, '''Concentration''' by taking advantage of physical and surface chemical properties, and '''Dewatering''' or solid/liquid separation.
[[Category:Adventist Youth Honors Answer Book|{{SUBPAGENAME}}]]
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A number of auxiliary [[materials handling]] operations are also considered a branch of mineral processing such as storage (as in bin design), conveying, sampling, weighing, slurry transport, and pneumatic transport.
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== Ca&Ba ==
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[[Comminution]] is particle size reduction of materials.  Comminution may be carried out on either dry materials or slurries.  [[Crushing]] and [[grinding]] are the two primary comminution processes.  Crushing is normally carried out on "run-of-mine" ore, while grinding (normally carried out after crushing) may be conducted on dry or slurried material.
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== Sizing ==
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Sizing is the general term for separation of particles according to size. 
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The simplest of sizing processes is screening, or passing the particles to be sized through a screen or number of screens.  Screening equipment can include grizzlies, bar screens, and wire mesh screens.  Screens can be static (typically the case for very coarse material), or they can incorporate mechanisms to shake or vibrate the screen. 
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Classification refers to sizing operations that exploits the differences in settling velocities exhibited by particles of different size.  Classification equipment may include [[ore sorters]], gas cyclones, hydrocyclones, rake classifiers, rotating trommels, or fluidized classifers.  When the feed material contains particles of different densities as well as particles of different size, a degree of concentration takes place during classification because settling velocities are also dependent on particle density.
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== Froth flotation ==
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[[Froth flotation]] is achieved when particles are separated based on their surface potential. Hydrophobic particles are recovered to the froth, whereas hydrophilic particles are discharged with the tailings stream. Some mineral particles are naturally hydrophobic, whereas others require specific reagent additions to change their surface potentials.[[Oxide]] ores, such as [[spodumene]] and [[tantalite]] can be treated using [[oxalic acid]] based collectors. [[Sulfide]] ores can be recovered using xanthate or dithiophosphate type collectors.
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== Gravity concentration ==
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Particles can be classified based on their [[specific gravity]]. Gravity concentration processes include:
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* Heavy media or dense media separation
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* Shaking tables, such as the wilfely table
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* Spirals
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* Centrifugal bowl concentrators
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* Jig concentrators. [http://www.gekkos.com Gekko Systems] is a manufacturer of the InLine Pressure Jig (IPJ), a continuous processing gravity concentration device.
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# Multi gravity separators
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# Nelson concentrators
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== Electrostatic separation ==
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Non-conducting particles maintain an electrostatic charge induced electrically, and so remain pinned to a charged drum.  Conducting particles do not maintain the electrostatic charge and so fall off the drum, thus minerals such as [[ilmenite]] and [[rutile]] can be separated.
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== Magnetic separation ==
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Minerals such as [[magnetite]] and [[pyrrhotite]] are naturally [[magnetic]], and so can be separated from non-magnetic particles using strong magnets.
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== External links ==
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*[http://www.min-eng.com/general/bookstore/1.html  Wills' Mineral Processing Technology, 7th Edition, B.A. Wills and T.J. Napier-Munn, Elsevier, 2006]
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*[http://www.min-eng.com/ Minerals Engineering International]
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[[Category:Metallurgy]]
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[[fi:Rikastus]]

Revision as of 07:21, 3 May 2007

Mineral processing, otherwise known as mineral dressing, is the practice of beneficiating valuable minerals from their ores. Industrial mineral treatment processes usually combine a number of unit operations in order to liberate and separate minerals by exploiting the differences in physical properties of the different minerals that make up an ore.

Many plants also incorporate hydrometallurgical or pyrometallurgical processes as part of an extractive metallurgical operation.

Mineral processing involves four general types of operations: Comminution or particle size reduction, Sizing or separation of particle sizes by screening or classification, Concentration by taking advantage of physical and surface chemical properties, and Dewatering or solid/liquid separation.

A number of auxiliary materials handling operations are also considered a branch of mineral processing such as storage (as in bin design), conveying, sampling, weighing, slurry transport, and pneumatic transport.

Ca&Ba

Comminution is particle size reduction of materials. Comminution may be carried out on either dry materials or slurries. Crushing and grinding are the two primary comminution processes. Crushing is normally carried out on "run-of-mine" ore, while grinding (normally carried out after crushing) may be conducted on dry or slurried material.

Sizing

Sizing is the general term for separation of particles according to size.

The simplest of sizing processes is screening, or passing the particles to be sized through a screen or number of screens. Screening equipment can include grizzlies, bar screens, and wire mesh screens. Screens can be static (typically the case for very coarse material), or they can incorporate mechanisms to shake or vibrate the screen.

Classification refers to sizing operations that exploits the differences in settling velocities exhibited by particles of different size. Classification equipment may include ore sorters, gas cyclones, hydrocyclones, rake classifiers, rotating trommels, or fluidized classifers. When the feed material contains particles of different densities as well as particles of different size, a degree of concentration takes place during classification because settling velocities are also dependent on particle density.

Froth flotation

Froth flotation is achieved when particles are separated based on their surface potential. Hydrophobic particles are recovered to the froth, whereas hydrophilic particles are discharged with the tailings stream. Some mineral particles are naturally hydrophobic, whereas others require specific reagent additions to change their surface potentials.Oxide ores, such as spodumene and tantalite can be treated using oxalic acid based collectors. Sulfide ores can be recovered using xanthate or dithiophosphate type collectors.

Gravity concentration

Particles can be classified based on their specific gravity. Gravity concentration processes include:

  • Heavy media or dense media separation
  • Shaking tables, such as the wilfely table
  • Spirals
  • Centrifugal bowl concentrators
  • Jig concentrators. Gekko Systems is a manufacturer of the InLine Pressure Jig (IPJ), a continuous processing gravity concentration device.
  1. Multi gravity separators
  2. Nelson concentrators

Electrostatic separation

Non-conducting particles maintain an electrostatic charge induced electrically, and so remain pinned to a charged drum. Conducting particles do not maintain the electrostatic charge and so fall off the drum, thus minerals such as ilmenite and rutile can be separated.

Magnetic separation

Minerals such as magnetite and pyrrhotite are naturally magnetic, and so can be separated from non-magnetic particles using strong magnets.

External links