high chrome grinding ball for mining industry

grinding ball

Cr10% (Hardalloy)

Hardness:60-64 HRC

Core/surface Hardness difference≤1.5HRC 

Ball falling resistence≥26000

Breakage≤1%

█Guarantees

Against Breakage:

1. Standard guarantees (in normal working conditions) If the breakage is confirmed :

Limited to 3000 running hours:

Between 0-1%: no claim Limited to 3000 running hours:

Between 1-3%: free of charge replacement of the corresponding quantity of broken balls. Above 3% : free of charge replacement of the entire batch of the particular affected dimension. Above 3000 running hours:

The quantity of broken balls will be seen as wear and tear and will be included in attached clauses(Guarantees against wear and Deformation)

Against Deformation or ovalization (out –of –roundness):

Standard guarantees ( in normal working conditions ) Admitted ovalization for balls of 1st chamber: 15%

If the ovalization for one diameter is higher than 15% before 2 years of operation ,the supplier will replace the balls as follows:

Against wear (expressed in g/kwh):

1. Standard wear guarantees ( in normal working conditions –see annex n 1 2 3): The total wear rate for both cambers is limited at :

a) 1.0 g/kwh for all conventional 2 chamber close circuit compound cement mills.

b) 1.2 g/kwh for all conventional 2 chamber open circuit mills.

c) 0.8 g/kwh for all grinding ball mill following a pre grinder (roller press or vertical mill) provided the pre-ground clinker fed to the ball mill has a fineness above 1400 Blaine.

The calculated achieved wear rate “Wa” will be confirmed after a period of time at least above or equal to 6000 running hours. The real wear rate figures should be properly defined after weighting the whole remaining ball charge ( sorting are supposed to be done every year for fist chambers and once every tow years for second chambers ),and taling into account each and every top-ups performed in course of this period of time.

In such a proper approach ,the wear rate achieved “Wa” should be defined a follows : Wa= Co+Tu-Cf x10 6

Tcem

█Metallurgical composition and structure:

Oil quenched structure (martensite+austenite+bainite) +chromium carbides K1 and K2 Metallurgical texture (free of any pearlite and ferrite soft phases )combining a fine and homogeneous Martensitic matrix and a well reguiarly distributed network of K1 and fine secondary K2 globular carbides (Fe, Cr)7C3 (hardness-1400HV)