ADDITIVE FOR GRINDING ON ROLLING MILLS

Abstract

At least one glycol compound is used as a grinding aid when grinding at least one solid substance, in particular an inorganic and/or mineral solid substance, in a rolling mill, wherein the at least one glycol compound has a structure according to formula I: (formula 1) and wherein a) R1, R2, R3 each independently of one another stand for H or an alkyl, alkoxy or alkanol group with 1-8 carbon atoms, in particular with 2-4 carbon atoms; and b) X stands for a substituted or unsubstituted alkylene group with 1-8 carbon atoms, in particular 1-4 carbon atoms.

Claims

1. A method for grinding, comprising grinding of at least one solid in the presence of at least one glycol compound, as a grinding aid, in a roller mill, the at least one glycol compound having a structure as per formula I: ##STR00005## where a) R.sup.1, R.sup.2, and R.sup.3 each independently of one another are H or an alkyl, alkoxy or alkanol group having 1-8 carbon atoms; and b) X is a substituted or unsubstituted alkylene group having 1-8 carbon atoms.

2. The method as claimed in claim 1, wherein the at least one glycol compound is selected from the group consisting of ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, butyl diglycol, neopentyl glycol, and hexylene glycol.

3. The method as claimed in claim 2, wherein the at least one glycol compound is selected from propylene glycol, dipropylene glycol, and butyl diglycol.

4. The method as claimed in claim 3, wherein the at least one glycol compound is selected from dipropylene glycol and butyl diglycol.

5. The method as claimed in claim 1, wherein the at at least one glycol compound is used for reducing vibration of the roller mill.

6. The method -t-t&e as claimed in claim 1, wherein the at least one glycol compound is used to stabilize a grinding bed of the roller mill.

7. The method as claimed in claim 1, wherein the at least one glycol compound is used for boosting the productivity of the roller mill and/or for increasing the fineness of grind of the at least one solid.

8. The method as claimed in claim 1, wherein the at least one glycol compound is employed together with at least one further additive, the further additive being selected the group consisting of grinding aids, defoamers, dyes, preservatives, plasticizers, superplasticizers, accelerators, retarders, air entrainers, shrinkage reducers and corrosion inhibitors.

9. The method as claimed in claim 8, wherein the further additive comprises at least one of the following representatives: a) one or more amino alcohols and/or salts thereof, b) one or more glycols and/or glycol derivatives, c) one or more polycarboxylates and/or polycarboxylate ethers.

10. The method as claimed in claim 1, wherein the solid comprises a mineral binder and/or an adjuvant for a mineral binder.

11. The method as claimed in claim 1, wherein the solid comprises at least 5 wt % of a hydraulic binder.

12. The method as claimed in claim 1, wherein the solid to be ground is admixed, before and/or during grinding, with the at least one glycol compound.

13. A grinding aid composition comprising a) at least one glycol compound, and b) at least one further additive which is selected from the group selected from the group consisting of grinding aids, defoamers, dyes, preservatives, plasticizers, superplasticizers, accelerators, retarders, air entrainers, shrinkage reducers and/or and corrosion inhibitors, wherein the at least one further additive is chemically distinguishable from the at least one glycol compound, and the at least one glycol compound has a structure as per formula I: ##STR00006## where R1, R2. and R3 each independently of one another are H or an alkyl, alkoxy or aikanol group having 1-8 carbon atoms, and X is a substituted or unsubstituted alkylene group having 1-8 carbon atoms.

14. A composition comprising a solid and at least one glycol compound, the at least one glycol compound having a structure as per formula I: ##STR00007## where R1, R2. and R3 each independently of one another are H or an alkyl, alkoxy or alkanol group having 1-8 carbon atoms; and X is a substituted or .sup.-in/substituted alkylene group having 1-8 carbon atoms.

15. The grinding aid composition as claimed in claim 13, wherein the at least one glycol compound is selected from the group consisting of propylene glycol, dipropylene glycol, and butyl diglycol.

16. A composition obtainable by a method as claimed in claim 12.

Description

WORKING EXAMLPES

[0109] 1. Additives Used

[0110] Additives A1-A7 below were used for the working examples (Table 1):

TABLE-US-00001 TABLE 1 Designation Composition A1 Ethylene glycol A2 Diethylene glycol A3 Propylene glycol A4 Dipropylene glycol A5 Butyl diglycol A6 Neopentyl glycol A7 Hexylene glycol

[0111] All of the substances A1-A7 listed in Table 1 are available commercially from various suppliers and were used in pure form (purity >97%).

[0112] 2. Laboratory Ball Mill Grinding Trials (Comparative)

[0113] For purposes of comparison, the activity of the various additives A1-A7 as grinding aids was investigated on a laboratory ball mill.

[0114] In grinding trials 1_1-L7, 300 g of a cement clinker were ground under identical conditions on a laboratory ball mill with each of the additives specified in Table 2. Trial L0 is a reference sample without additive. The levels of addition of additives A1-A7 were consistently 0.02 wt % (amount of pure additive, based on cement clinker). The grinding time was kept constant for all of the grinding trials.

[0115] When the grinding operation had taken place, the Blaine fineness and also the sieve residue of the particles above 32 μm (in wt %, based on all of the particles) were determined in analogy to standard EN 196-6 (May 2010) using a 32 μm sieve.

[0116] Table 2 provides an overview of the grinding trials conducted and of the corresponding results.

TABLE-US-00002 TABLE 2 Trial L0 L1 L2 L3 L4 L5 L6 L7 Additive — A1 A2 A3 A4 A5 A6 A7 Fineness in % 100 132 146 148 139 141 140 151 relative to L0 Sieve residue 100 78 69 66 71 71 72 66 >32 μm in % relative to L0

[0117] From Table 2 it is apparent in particular that the greatest fineness and also the smallest sieve residue are achieved when using additive A7 (trial L7).

[0118] With regard to fineness, therefore, the ranking list is as follows (higher values are better): A7>A3>A2>A5>A4>A1. With regard to fineness, accordingly, the ranking list is essentially the same (lower values are better): A7=A3<A2<A5=A4<A1.

[0119] 3. Roller Mill Grinding Trials

[0120] The various additives A1-A7 were then used as grinding aids on a roller mill with downstream classifier. The roller mill was operated so as to grind the cement clinker to a constant specific Blaine surface area of 4200 cm.sup.2/g. For the determination of the grinding efficiency and/or the effect of the grinding aids, the production quantity of ground cement per unit time (in metric tons per hour) was measured. Additionally, the vibrations during the grinding operation were ascertained.

[0121] The mill was operated with the following parameters: [0122] Grinding plate rotary speed: 98 revolutions/min [0123] Grinding pressure: 150 bar [0124] Classifier speed: 650 revolutions/min [0125] Fresh air supply: 480 m.sup.3/h [0126] Temperature (after classifier): 90° C.

[0127] Table 3 provides an overview of the grinding trials conducted and of the corresponding results (R0 is a reference sample without additive).

TABLE-US-00003 TABLE 3 Trial R0 R1 R2 R3 R4 R5 R6 R7 Additive — A1 A2 A3 A4 A5 A6 A7 Productivity in % 100 116 118 119 121 118 115 120 relative to R0 Vibration 10 10 6 4 3 4 8 8 [mm/s]

[0128] Table 3 shows clearly that additives Al-A7 are suitable grinding aids for roller mills and produce an increase in the productivity or grinding efficiency. Scoring particularly well in these trials are the additives A3 (propylene glycol), A4 (dipropylene glycol), and A7 (hexylene glycol).

[0129] With regard to productivity, therefore, the ranking list is as follows (higher values are better): A4>A7>A3>A5=A2>A1>A6.

[0130] Particularly surprising are the vibration values observed: the additives A3 (propylene glycol), A4 (dipropylene glycol), and A5 (butyl diglycol) produce particularly high reductions in the unwanted vibrations.

[0131] With regard to vibration, therefore, the ranking list is as follows (lower values are better): A4<A5=A3<A2<A6<A7<A1. This sequence is clearly different from the above-recited sequence relating to the productivity.

[0132] A comparison with the results from Table 2 shows that the same grinding aids act completely differently in grinding media mills (e.g., ball mills) than in roller mills.

[0133] Hence it has been shown, in particular, that through the use of a glycol compound as grinding aid in the grinding of solids, especially in cementitious binders, in a roller mill, it is possible to achieve a massive boost to the productivity and a significant reduction in mill vibration.

[0134] The embodiments described above should be understood, however, merely as illustrative examples, which may be modified as desired within the bounds of the invention.