*Principles of Size Reduction by CrushingTB. SURYAMAN3334140204

Teknik MetalurgiUniversitas Sultan Ageng Tirtayasa

Workshop Guru PKM FST UAI 19 Des 09

2OutlineIntroductionProcessing Approach and Method

Principles Size Reduction by CrushingLiberation and Cominution

Conclusion

IntroductionWHAT CONSTITUTES MINERAL BENEFICIATION?

Ore is an aggregate of minerals and contains valuable and gangue minerals . The mineral beneficiation involves separation of gangue minerals from ore. It has three steps Liberation , Separation, Concentration.

Liberation of valuable mineral by size reduction. Separation of coarse and fine particles.Concentration to separate the gangue minerals to increase the metal grade.

If the first step is not done correctly, the second step will be incomplet

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Processing Approach and Methodmineral processing consists of two functionsLiberationSeparation

These functions are carried out within the constraints of the following three rules.The first rule deals with the conservation of mass. The total flow of the material into the process plant equals the total flow out.The second rule relates to the quality or grade of the concentrate product. In practice, it is impossible to produce a concentrate consisting of only one mineral.The third rule is a corollary of the second. It is impractical to recover all of the valuable minerals into the concentrate.

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LIBERATION AND COMINUTIONLIBERATION BY SIZE REDUCTION. Consider a cube ( 10 cm dia )of the ore having MINERAL and GANGUE. Suppose it has cubic grains of 10 mm. Assumptions crushing is conducted to yield grains of same size. crystals in the ore are intimately joined with each other.

Till the ore lump is crushed to 10 mm dia, all grains are locked. If the ore lump is crushed to particles of 5 mm dia, some grains are FREE and some are LOCKED. It cannot be assumed that all particles are free since they are of 5 mm dia ( smaller than 10 mm dia). Locked grains 5 =10 x10 mm 5

LIBERATION BY SIZE REDUCTION.

MINERALS OF EQUAL ABUNDANCE. 6

7COMINUTIONWhen raw materials are processed in solid state, particle size reduction is essential. The ROM ore may be as big as 3 m in size.Minerals should be liberated before concentration. This liberation accomplished by comminutionCOMMINUTION - The whole operation of reducing the raw ore to the size required for mechanical separation or metallurgical processing. It is used to create particles in a certain size and shape, increase the surface area available for next process liberate valuable minerals held within particles

8LIBERATION AND COMINUTIONCOMINUTIONBreaking of larger material to smaller pieces result in particles with varying degrees of liberation. The darker regions represent the valuable mineral

COMINUTIONOPERATING VARIABLES Comminution of the ROM ore is affected by 5 variables. Moisture content of solids.Moisture < 3-4 % by wt. no difficulties. Moisture content > 4wt%- Ores become sticky, clog the machines 2. Reduction ratio ( RR ). Average diameter of the feed / average diameter of the product. In primary crushers , RR = Gape / Set. Gape- Size of the receiving opening ( max size acceptable in the machine). Set - Size of discharging opening ( max. size passing through the discharge end). Normal RR - 3-7 ( for coarse crushing ),

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COMINUTION3. Hardness An arbitrary scale of hardness has been devised known as Mohs Scale; Mohs Scale = 1 is for graphite Mohs Scale < 3 is for soft material Mohs Scale > 7 is for hard material Mohs Scale = 10 is for diamondThe harder the material the more difficult it is to reduce in size

4. AbrasivenessAbrasiveness is a property of hard materials (particularly those of mineral origin).

Workshop Guru PKM FST UAI 19 Des 09*

Workshop Guru PKM FST UAI 19 Des 09

COMINUTION5.Closed / open circuit operation. 11

Principles of size reduction by crushing12

Principles of size reduction by crushingImpact particle concussion by a single rigid force (hammer).

13HAMMER MILL

Principles of size reduction by crushingAttrition arising from particles scraping against one another or against a rigid surface (a file).

BALL MILL14ROD MILL

BALL MILL

Principles of size reduction by crushing15Compression equipments

Mesin Kominusi dan Gaya serta Distribusi Ukuran yang Dihasilkannya16

GayaAlatProdukSifat GayaMetodeCompression Jaw, Gyratory, rollSelang ukuran sangat sempitPembebanan relatif lambatBijih ditekan diantara dua benda (plat baja) kerasImpactHammer mill, ImpactorSelang ukuran sangat lebarPembebanan relatif cepatBijih dibentur, dibanting, dipukul pada/oleh benda kerasAttritionBall mill, Rod millSangat halusPembebanan relatif lambatBijih terkikis, digesek pada bagian permukaan

CONCLUSION Ore is an aggregate of minerals and contains valuable and gangue minerals .mineral processing consists of two function are Liberation and SeparationCOMMINUTION - The whole operation of reducing the raw ore to the size required for mechanical separation or metallurgical processing.There are 5 variable can be affected the cominution process are moisture content of solids, reduction ratio ( RR ), hardness, abrasiveness and closed / open circuit operation. The priciples of size reduction are impact, attrition, shear and compression

Workshop Guru PKM FST UAI 19 Des 09*

Workshop Guru PKM FST UAI 19 Des 09

REFERENCES18Ish Grewal, M.A.Sc. P.Eng. Mineral Processing Introduction. http://met-solvelabs.com/library/articles/mineral-processing-introduction. (diakses pada sabtu, 19 september 2015)

Kelly, Errol G. Dan David J. Spottiswood. 1982. Introduction to Mineral Processing. New York: John Willey & Sons.

Syed Tanveer. Mineral Processing. http://www.slideshare.net/SyedTanveer3/mineral-processing-34715065?qid=3b05409a-d669-4dc1-b532-82aa58b72ee3&v=default&b=&from_search=9(diakses pada minggu, 20 september 2015)

Anonim. Pengolahan Mineral. http://ardra.biz/sain-teknologi/mineral/pengolahan-mineral/kominusi-operasi-pengecilan-ukuran/(diakses pada minggu, 20 september 2015)

THANK YOU19The End

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