DecouplThroughPress

Idea
purpose, advantages, inventor

Research
comminution, material throughput, pressure distribution, modelling

Praxis
plant configuration, roller wear, references

Literature
literature survey, references

Other Links
links to suppliers, universities and other institutions

Contact
for any questions please contact us

Site-Map
all pages at a glance


	Decoupling of Throughput and Comminution


	Grinding force, circumferential speed and roller surface structure respectively roller profile have an influence on the comminution as well as on the throughput. Therefore it can be expected that there is a mutual influence. However the grinding force will especially have an impact on the comminution whereas the circumferential speed will especially affect the throughput. The question of the decoupling of both target parameters has to be asked. Former results already indicated this [2,5]. In the following it will be stated how far a decoupled treatment is acceptable in the studied range.



	Throughput of quartz and limestone, smooth rollers (g) and with profile (p) / Institute for Mineral Processing of the Technical University Clausthal (Germany, 1989)

	The diagram above shows the throughput of a coarse and a fine graining for limestone with smooth rollers and for quartz with smooth and moulded rollers against the specific grinding force. The roller speeds are 0,3 and 1,0 m/s. The results show exemplary for all other test parameter settings that the throughput is nearly independet of the grinding force for a wide range of particle sizes and also for moulded rollers; the biggest decrease of throughput with an increase of the sp The diagram below shows also exemplary the product particle size distributions of the coarse quartz and limestone grainings at a roller speed between 0,3 and 3,3 m/s and specific grinding forces of approximately 2,3 N/mm²; the rollers were moulded. In all cases the particle size distriobution is independet of the roller speed.This result was also found for other grainings and for smooth rollers.

Comminution
grinding results for different materials

Exper. Setup
lab-scale mill, techn. data mill, intrumentation, feed materials, testing program, roller surface data, test execution

Throughput
literature, decoupling of throughput and comminution, energy absorption, characteristic of different rollers, phenomenons, throughput results, elasticity, friction angle, specific throughput

Pressure Distribution
pressure diagrams

Press Tests
tests with a molding press

Modelling
mathematic model of the process

Signs and Symbols
nomenclature




	One-passage grinding of quartz and limestone, 1.6/6.3 mm, profile B (1-8-3/4) / Institute for Mineral Processing of the Technical University Clausthal (Germany, 1989)

	But at the same level of specific grinding force the comminution effect may depend on the roller surface structure. In the diagram below the product particle size distributions for a coarse quartz graining 1,6/6,3 mm after a stressing with 2,3 N/mm² respectively 2,8 N/mm² with smooth and moulded rollers are compared. With profile B the grinding effect is lower but the throughput of 5,3 t/h is much higher than the throughput of 2,0 t/h with smooth rollers.The energy absorption which is resulting out of this is 4,1 J/g for moulded and 8,2 J/g for smooth rollers.



	One-passage grinding of quartz, 1.6/6.3 mm, u ~ 1 m/s / Institute for Mineral Processing of the Technical University Clausthal (Germany, 1989)

	This explains the different fineness as it is generally known that the comminution effect is a function of the energy absorption. For the limestone graining 0,1/1,6 mm the particle size distributions are nearly the same, see diagram below. The throughput shows only little differences with 1,24 t/h and 1,64 t/h. The energy absorption is 3,8 respectively 3,7 J/g.The small increase in throughput with moulded rollers is exlained by the build-up of a coating layer on the roller surface. This phenomenon is discussed in the chapter throughput characterisitc.



	One-passage grinding of limestone, 0.1/6.3 mm, u ~ 0.3 m/s / Institute for Mineral Processing of the Technical University Clausthal (Germany, 1989)

	In the next two diagrams the specific grinding work W_M - needed for a product fineness x_P < 1,6 mm respectively x_P < 0,1 mm - is plotted versus the specific grinding force. W_M is the qoutient of energy absorption E_M and the portion of fines f(x_P) below 1,6 mm respectively 0,1 mm: W_M = E_M / [Q_P(x_P) - Q_A(x_P)].



	Specific grinding work for the grinding of 1.6/6.3 mm finer than 1.6 mm / Institute for Mineral Processing of the Technical University Clausthal (Germany, 1989)



	Specific grinding work for the grinding of 0.1/6.3 mm finer than 0.1 mm / Institute for Mineral Processing of the Technical University Clausthal (Germany, 1989)

	In each case the test results with smooth and moulded rollers arrange themselves around a balancing curve. This means that energy absorption and portion of fines behave nearly proportional. In the attached spreadsheet several energy and throughput figures are shown. So the results show that throughput and comminution can be treated as almost decoupled in the studied range.


	[HCRM-Home] [Idea] [Research] [Praxis] [Literature] [Other Links] [Contact] [Site-Map]


	For any questions or remarks please contact the Webmaster. © Copyright 1992, Dr. Uwe Lubjuhn, all rights reserved