Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B02—CRUSHING, PULVERISING, OR DISINTEGRATING; PREPARATORY TREATMENT OF GRAIN FOR MILLING
  • B02C—CRUSHING, PULVERISING, OR DISINTEGRATING IN GENERAL; MILLING GRAIN
  • B02C21/00—Disintegrating plant with or without drying of the material
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B02—CRUSHING, PULVERISING, OR DISINTEGRATING; PREPARATORY TREATMENT OF GRAIN FOR MILLING
  • B02C—CRUSHING, PULVERISING, OR DISINTEGRATING IN GENERAL; MILLING GRAIN
  • B02C4/00—Crushing or disintegrating by roller mills
  • B02C4/02—Crushing or disintegrating by roller mills with two or more rollers

Definitions

• the invention deals with a method for milling of material with different grain size and/or with different range of grindability from 30 up to 90 according to Hargrowe (Hg) in more, mutual consequential milling steps, with using of middle-pressure roll presses.
• a disadvantage of the present procedures is, that during concurrent milling of several components with different value of grindability, for example in vertical roller mills, the components with higher grindability are over-milled and the components with lower grindability are under-milled. Than, it is necessary to repeat the milling of significant part of under-milled components. Such milling processes necessarily cause higher consumption of energies, what results in lower specific output of the milling system.
• the aim of the invention is, that during concurrent milling of several components with different value of grindability, for example in vertical roller mills, the components with higher grindability are over-milled and the components with lower grindability are under-milled.
• Such milling processes necessarily cause higher consumption of energies, what results in lower specific output of the milling system.
• Further essence of the invention is, that at least between the first and the second milling step, further material is added to the milled material and that type and/or grindability of added material is different from grindability of admission milled material, advantageously material with lower grindability, than is that of material in previous step.
• the procedure is according to the invention divided into three separate, mutually functionally defined steps, it is possible to adjust the operating conditions in the first one, so that the material with bad grindability, possibly mixture of such materials, is processed preferentially, efficiently from the functional and economical point of view.
• it is possible advantageously to dose additionally materials with better grindability to further milling step, possibly materials with lower grain size.
• Example 1 Method of milling according to the invention is in this example used for milling of material with practically the same grindability, for example cement clinker, after its exit from rotary kiln followed by inserted cooler. It is dealing with a material with middle grindability (Hg 80), but with significant different grain size, usually in the range from 0,1 to 45 mm.
• the cement clinker is according to Fig. 1 collected in the reservoir 4, from there it is through the piping 40 lead to the milling bodies of the first used milling stage 1, for example in form of a roll middle-pressure press of standard construction, with the rest slot adjusted to 27 mm. There, supplied cement clinker is pre-formed, especially larger admission grains are being broken.
• the pre-formed cement clinker is transferred by the means of the first transport element 10 to the second milling stage 2, for example again to a middle-pressure press, its not illustrated operating slot is adjusted on value of 15 mm, e.g. lower than that in the previous step and on the contrary, thrust of the milling roll is higher.
• the pre-formed cement clinker which already doesn't contain grains of significantly different size, is pre-milled and simultaneously calibrated as to height, so that a layer of practically homogenous material, as to grain size and compactness, is produced.
• the material is than transferred by the means of the second transport element 20 to the third milling stage 3.
• the operating slot of this stage is adjusted on the value of 10 mm, thrust of the milling roll is on the contrary even higher than the thrust in the previous milling stage.
• the material is after-milled to the final requested size and the result product is through the outlet 30 lead towards the further technological step.
• a sorting system 6 is inserted according to Fig. 4 after the outlet 30 from the third milling stage 3, the system contains a separator 60, consisting for example of suitable chosen vibrating screen, air separator and so on. Sufficiently finely milled cement clinker passes through the separator 60 and is lead through the outlet 61 towards further technological step. Separated undesirable coarser fraction is through the discharge 62 and connected return transport element 620, for example a transporter, lead to the additional reservoir 51 and from there through the piping 510 and the first transport element 10 back to the second milling stage 2.
• a separator 60 consisting for example of suitable chosen vibrating screen, air separator and so on.
• Sufficiently finely milled cement clinker passes through the separator 60 and is lead through the outlet 61 towards further technological step.
• Separated undesirable coarser fraction is through the discharge 62 and connected return transport element 620, for example a transporter, lead to the additional reservoir 51 and from there through the piping 510 and the first transport element 10 back to
• Procedure according to the invention is used for preparation of mixed cement, which consists of 70% till 94% of mixture of cement clinker with average grindability of 75 Hg and with predominantly higher share of grains with larger dimensions, of 6% till 35% of slag with average grindability of 35 Hg, which has larger share of grains with small dimensions and of 5% of soft gypsum with average grindability of 95 Hg.
• Example of procedure of milling of above mentioned components is illustrated in variants on Fig.2 and is as follows.
• the first milled component is the cement clinker, dosed from the reservoir 4 through the piping 40 to the first milling stage 1.
• the slag is dosed into the second milling stage 2 from the additional reservoir 51, e.g. the mixture of slag and cement clinker is entering it.
• the gypsum with the best grindability is dosed from the additional reservoir 52 ' through the piping 520 to the third milling stage 3 together with pre-milled mixture of slag and cement clinker.
• Procedure according to this example is a variant of preparation of mixed cement in composition according to previous example.
• the first two materials e.g. cement clinker and slag
• the first two materials are stored in the first reservoir 41 and the second reservoir 42, as is illustrated on Fig.3, from there, they are through the pipings 410 and 420 dosed into the common reservoir 4 and consequently through the piping 40 lead to the first milling stage 1 with relatively large operating slot and with low thrust of not illustrated milling roll.
• the remaining component of prepared mixed cement e.g. soft gypsum
• the additional sorting system 21 is advantageously inserted into the milling line yet before the final phase of after-milling.
• Its separator 210 separates undesirable, so far insufficiently milled material, which exits the second milling stage 2 and it also transfers sufficiently fine fractions through the transport element 211 to the third milling stage 3.
• Possible coarser under-milled fraction is, on the contrary, by the return transport element 220 returned to the second milling stage 2, namely through the additional reservoir 51 or directly by the means of the first transport element 10, as is illustrated on Fig.3 in broken line.
• blast furnace cement which consists of mixture of 65% to 80% of blast furnace slag, 20% to 35% of cement clinker and 5% of gypsum, namely according to the procedure illustrated on Fig.4.
• the first milled component is a slag dosed from the reservoir 4 through the piping 40 into the first milling stage.
• Cement clinker and gypsum with lower grindability is dosed from the additional reservoir 51 to the second milling stage 2 together with slag, exiting the first milling stage 1.
• Mixture of all three components, necessary for preparation of the blast furnace cement, is than dosed by the means of the second transport element 20 to the third milling stage 3 for after-milling and it exits it through the outlet 30 towards further technological step.
• Possible application of the sorting system 6 was described in connection with example 1.
• Method for milling of materials with different grain size and large range of grindability can be advantageously used especially for milling of recycled matters, cement clinker with admixture of slag, puzzolan, ash and so on, possibly for milling of two or more types of minerals with recycling of fractions and during fining of mixtures.

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• Engineering & Computer Science (AREA)
• Food Science & Technology (AREA)
• Crushing And Grinding (AREA)
• Disintegrating Or Milling (AREA)

Priority Applications (2)

Applications Claiming Priority (2)

Publications (1)

Family

ID=5462514

Family Applications (1)

Country Status (4)

Cited By (2)

Citations (9)

• 1999
  • 1999-03-18 CZ CZ1999949A patent/CZ292488B6/cs not_active IP Right Cessation
• 2000
  • 2000-03-14 BR BR0010773-5A patent/BR0010773A/pt not_active IP Right Cessation
  • 2000-03-14 SK SK1417-2001A patent/SK284706B6/sk not_active IP Right Cessation
  • 2000-03-14 WO PCT/CZ2000/000014 patent/WO2000056457A1/en not_active Ceased

Patent Citations (9)

Non-Patent Citations (1)

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