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Chromium

Chromium

Release time:23 August 2019
Chromium

Type
Element (Minerals/Ores of)

Mineral Classification
Oxide

Chemical Formula
(Fe, Mg)Cr2O4

Streak
Brown

Mohs Hardness
5.5

Crystal System
Isometric

Color
Black to brownish black; brown to brownish black on thin edges in transmitted light

Luster
Submetallic

Fracture
Uneven

Description

Chromium (Cr) is a hard, bluish metallic element. The only ore of chromium is the mineral chromite and 99 percent of the world’s chromite is found in southern Africa and Zimbabwe. Geologists estimate that there are about 11 billion tons of mineable chromite ore in the world, enough to supply the current demand for hundreds of years. It is mostly used for making stainless steel and other metal alloys.

Relation to Mining

While China is the leading chromium-consuming country and the leading stainless steel producer, it is not a large producer of chromite ore. The United States, Kazakhstan, India and South Africa are the largest chromite-mining countries in the world. The mining method used for extracting the chromite depends greatly on the characteristics of the deposit. These characteristics include whether it is stratiform or podiform, high grade or low grade, subsurface or near the surface, or massive or disseminated. Because surface mining typically is less expensive than underground mining, it is preferred, but not always possible.

Like mining, beneficiation (processing, crushing, separating, smelting, refining, etc.) for chromite depends on the characteristics of the ore deposit and on the mining methods used. For example, an operation extracting only high-grade ore may require only hand sorting and screening. Beneficiation is necessary when chromite mineral is mixed with other minerals because of geologic conditions or when mechanized mining methods are nonselective.

Uses

Chromium is alloyed (that is, mixed) with steel to make it corrosion-resistant or harder. An example is its use in the production of stainless steel, bright, shiny steel that is strong and resistant to oxidation (rust). Stainless steel production consumes most of the chromium produced annually. Chromium is also used to make heat-resisting steel. So-called “superalloys” use chromium and have strategic military applications.

Chromium also has some use in the manufacture of certain chemicals. For example, chromium-bearing chemicals are used in the process of tanning leather. Chromium compounds are also used in the textile industries to produce a yellow color.

Related cases

Extract chrome from its ore

Chrome beneficiation methods

Chrome gravity separation

The gravity separation and magnetic separation process are the main chrome extraction beneficiation methods, chrome ore gravity mining equipment have jig separator, shaking table, spiral classifier, centrifugal concentrator and spiral chute. Sometimes, use weak magnetic separator or high-intensity magnetic separator to further improve the grade of chromium concentrate and the ratio of chromium iron. Besides, some chrome mines use flotation and flocculation flotation methods.

Chrome magnetic separation

How to determine the chrome ore concentrating method and select the right chrome mining equipment is closely related to the physical and chemical properties of chromium ore. Because chromite is weakly magnetic, with the development of high-intensity magnetic separation technology, the technology of purifying chromium ore with high-intensity magnetic separation has been very mature. Moreover, the magnetic separation process has no pollution to the environment, the chrome ore magnetic separation technology has been popularized and applied in the major mineral processing plants.

Mineral deposit and equipment

The most suitable flow and machine are varied by the condition of mine. Rock mine need crusher and ball mill in most cases, alluvial deposit mine is most for small size, trommel scrubber wash the clay, screen the big size out, and then separate the waste sand and mineral.

Crusher & ball mill & spiral classifier: this machine is for stone mine grind step, big size to crusher, after crusher to ball mill grinding, spiral classifier can make big size to ball mill grinding again.

Trommel scrubber & trommel screen & vibration screen: this machine is for washing and separates different sizes. Clay mine need trommel scrubber to washing, without clay ore need trommel screen and vibration screen to separator different size.

Shaking table & jig separator & centrifugal concentration & spiral chute: this machine is for concentration machine, is use gravity to separator gold, tin, coltan, chrome, diamond, tungsten and so on.

gold mining equipment
gold mining equipment
gold mining equipment
gold mining equipment1

Hard rock chrome mining process

Flow description

The raw ore should be crushed by jaw crusher initially. When it gets a reasonable fineness, it is transported into a vibrating screen through conveyor and feeder.
The screened ores get the next procedure: milling process in the ball mill, then next jigging separation. The milled ore gets into chrome jig separator for gravity separation.

Chrome ore is processed by crushing–screening–washing–selection or heavy medium separation for block granularity enrichment. Flowsheet of medium separation–jigging–milling–spiral beneficiation–intensity magnetic separation has been adopted widely, and flow sheet of shaking table–ore washing–dry normal magnetic separation–intensity magnetic separation–floatation separation is used to separate sea chrome sand.

The beneficiation Equipment flow produced by our company can provide you with all-around technical support. According to different customers and different chromite mine, JXSC custom made beneficiation processing lines for you.

Rock chrome processing machine

Feeder, jaw crusher, vibrating screen, cone crusher, ball mill, jigging machine, shaking table, drying system, magnetic separator, belt conveyor and so on. 2-300 TPH available.

Chrome processing flow chart

CHROME ORE BENEFICIATION FLOW SHEET

Successful case – rock chrome case

Rock chrome mine in Albania
JXSC help customer installed a 10 TPH hard rock chrome process plant in Albania in 2017.
capacity: 10 TPH
Feeding size: 300mm,

Feeding: hopper and vibration screen
Crushing: two-stage jaw crusher to crush raw material to 0-20mm.
Grinding: Grind the fine jaw crusher output material to 1mm. vibrating screen work together with the spiral classifier, 0-1mm size goes to shaking table, and +1mm are sent to ball mill grinding again.
Shaker table chrome gravity separation: Shaking table also has two stage, one for preliminary, one for fine. Adding the hydraulic box to feeding material to the shaking table, the hydraulic box also can separate different ore sizes to different shaking tables, course deck, fine sand deck, slime deck, thus get the highest recovery rate.

Stone-chrome-mine-in-Albania1
Stone-chrome-mine-in-Albania2

Alluvial chrome mining process

Alluvial chrome process flow

Feeding -> washing -> sieving -> primary gravity separation -> 2nd stage gravity concentration -> magnetic separation for upgrading

Chrome ore Feeding: can be vibration feeding machine, feeding hopper, belt feeder, wheel loader or excavator feed directly. Usually will add grizzly bar on the vibration feeder or hopper to remove big waste stones firstly. It depends on the process capacity to choose suitable chrome ore mining equipment.

Chrome ore Washing: the chrome ore washing machine is for washing clean the clay and mud in raw material, most popular used are chrome ore washing trommel scrubber and chrome ore washing trommel screen. Chrome ore trommel scrubber washer is for washing chrome ore raw material that with much sticky clay, chromite ore washing trommel screen is for wash chromite ore raw material that without much sticky clay. It depends on raw material conditions to choose suitable chrome ore washing equipment.

Chrome ore Sieving: after washing, then sieve out some bigger waste stones, the under-screen slurry will go to the next separation machine. This sieving process can use trommel screen or vibration screen or chrome ore high-frequency vibration screen which is widely used chrome ore mining equipment

Chrome ore Primary Gravity Separation: it is for primary chrome ore concentration process, jig separator or spiral chute separator are the best choices of chrome ore gravity mining equipment. The concentrated ore discharged from them will send to 2nd stage concentration machine.

2nd Stage Concentration process: the concentrate ore from chrome ore jig machine or spiral chute separator will go to chrome ore shaking table concentration machine for final concentration, can get high-grade chrome ore concentrate. Shaking table is a good concentration effect mining equipment for chrome ore processing plant.

Chromite ore refining: if need much higher chrome ore grade, can use high intensity magnetic separator to upgrade it. The chrome ore magnetic separator is also important chrome ore mining equipment for final upgrading.

Alluvial chrome flow chart

gold mining equipment

Chrome mining equipment manufacturer

JXSC Mine Machinery Company in China has more than 30 years experience in chrome ore equipment manufacturering, and ore processing flow design & optimization. Have already built many chrome ore processing plant in South Africa, Zimbabwe, Madagascar, Albania, India, Philippines, kazakhstan, Russia, China, etc.
Services: equipment supply, flow design, on site installation, sample test, visit factory invitation letter.

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