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CGB-Lab test 4 ( Cement water requirement )

[Feb 12,2020]

As CGB technology has increasingly caught the eyes of the global cement industry thanks to its remarkable performance in power saving,we’d like to share the lab test a couple years ago ( 2016 ) in China, which gives better picture on how to put this new technology into use properly after replacing steel ball.

1.Equipment

φ700mm×700mm  Lab Batch mill

It is equiped with torquemeter that can read the power consumption directly.Below is the technical parameter tables:

Item

Description Technical Data

1

Mill Shell Dimension

φ700×700mm  Effective. 600×600mm

2

Gear reducer

XW635       Raito:( 291)

3

Torquemeter

 HX-100

4

Motor

 Y132M47.5  Power7.5kW

5 Liner Shape

 Dragpeb

2.Clinker and FGD gypsum

Literally minimum 2 raw materials shall be used. However in order to avoid deviation due to heterogeneous mixture , one-component clinker was applied as raw materials during the test. When it came to the cement quality test, ground FGD ( Fuel Gas Desulfurization)gypsum is blended for various performance test.The technical data of the raw materials are as follow:

Clinker bond:

 13.3kWh/t

Milling method:

Roller press

Clinker Blaine:

 1133cm2/g

Clinker fineness:

 R45um=57%

FGD gypsum blaine:

9460cm2/g

3.Mill loading rate ( CGB -ceramic ball Vs steel ball)

During the test, both CGB and steel balls were set with loading rate at 24% with media scheme as below:  ( steel balls=174kgs,CGB= 84kgs, clinker charge=20kg/ each time)

Dia.,mm

30 25 20 15
Ratio,% 5% 23% 33% 39%

100%

4.Cement product water requirement analysis under standard consistency:

Below chart demonstrates at various blaines the cement fluidity variation ( initial and 60minutes ) for Steel ball and CGB-ceramic ball.

Item.

Steel ball

CGB-ceramic ball

Blaine Water Requirement Blaine

Water Requirement

cm2/g

% cm2/g %

1

3193 24.4 3244

24.8

2

3508 24.2 3356 24.4
3 3142 24.5 3250

24.5

4

3274 24.3 3245 24.5
5 3488 23.6 3380

24.2

6 3152 23.4 3558

24.4

7

3494

23.9

8

3549

24.1

Average

3350 24.1 3339 24.5

Above chart suggest, generally when CGB replace steel ball, there’s about 0.4% increase in water requirement for standard consistency.

5.Summary of this lab test

Item

Description Steel ball CGB

Comparison

1 Mill Power,% 100 86~98

Ave.↓5%

2 3~32μm,%* 56.39 60.88

↑4%

3

R45μm,% 11.3 7.5 ↓~4.0%
4 R80μm,% 2.4 1.3

↓~1.0%

5

28d Strength 54.2 56.1 ↑1.5~2MPa
6 Grain Distribution, n 0.87~0.91 0.93~0.97

↑~0.1

7

Water Requirement,% 24.1 24.5 ↑~0.4%

(Cement product blaine @ 3250cm2/g)

6.Summary:

① When steel balls serves as grinding media, the power consumption rate drop as the rotation rate go higher. However, when CGB works, the power consumption rate is more complicated. Mere rotation rate isn’t decisive element, the power saving target is also subject to the blaine. When the cement product blaine > 3300cm2/g ,rotation rate @ 7r/min, the main drive power consumption rate is minimized. However, when the cement product blaine <3300cm2/g,the power consumption rate see a increase against rotation rate goes higher though the variation is slight.

② As grinding media, given same rotation rate and low blaine target, CGB has remarkable competitive edge in power saving performance. When it comes to high blaine target, if there’s no any technical modification, the power saving performance of CGB will not be evident.

③ CGB features selectivity: at same blaine with CGB as grinding media, the R 45um witness 4% drop compared with steel balls, and 1% drop for R 80um. When CGB is introduced, the cement product homogeneity coefficient has a slight variation which result from the narrowed grain distribution.

④ As compared with steel ball, given same blaine, cement product ground by CGB witness a 0.2-0.4% increase in water requirement. Although the 3-day strength drop slightly,the 28-day strength are enhanced on the contrary. The cement product fluidity isn’t affected by the grinding media type,regardless of CGB or steel ball.

 
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