GM-2: High Chromium Cast Grinding Cylpebs for Cement & Mining Ball Mill

Key Advantages

Reduced consumption cost
High chromium grinding cylinders are harder than forged steel cylinders and can be produced with various chromium contents (10-28%). Used in ball mills, they are consumed at only 25%-65% of the rate of forged steel and lower chrome cast cylinders. For special minerals of the highest hardness, such as Quartz sand, select Top chromium (Cr: 23-28%) cast grinding media, whose consumption cost is far lower than that of other grinding media.

Greater hardness
After special heat treatment (Oil quench & annealing), High Chrome cast grinding steel cylinders reach the highest hardness (HRC 64- 66). Small cast cylinders of Φ6*6 - Φ30*35 mm can reach HRC 66, and cast cylinders of Φ30*35 - Φ55*60 mm can reach HRC64. This is the highest hardness compared with grinding media of any other material. In addition, the hardness difference between the surface and the core of these cast high chrome cylinders is under HRC 2.

Tailored alloy steel composition
To meet customer requirements, the NGZR foundry can adjust the chromium content (1.0-30%) of the chemical composition, along with other useful alloying elements such as C /Mn/ Si/ Cu/ Ni/ Mo etc. Together with special heat treatment, this gives the cast grinding cylinders different technical parameters, such as hardness / Impact Value / Breakage and de-shaping rate / micro- structure / resistance to high PH acid or alkali / high temperature resistance etc, to satisfy the customer's special needs.

Custom grinding media shapes
NGZR can design and produce grinding media in a variety of shapes: Grinding balls (Sphere), Grinding cylpebs ( Cylinder), Grinding eggs ( Ellipsoid), Polyhedron shapes and other special customized forms. Under different grinding conditions, different shapes give a better grinding effect.

Lower breakage & out-of-roundness rates
Thanks to controlled raw material quality, advanced casting equipment and special heat treatment, NGZR high chrome grinding cylinders have good physical properties. Large cast grinding media show a breakage & out-of-roundness rate below 1%, and small cast balls show one below 0.5%

Applications

High chrome cast grinding cylinders are consumable grinding media. Ball mills use them to crush and grind raw materials, such as lumps of mineral ore, into powder. The industries where they are applied include:

1. Mining
Widely applied in the mineral processing of iron, copper, gold, silver, lead-zinc, bauxite, nickel, manganese, chromium, lithium carbonate, graphite, fluoride and quartz mines, etc.

2. Cement industry
Employed in ball mills and roller machines to grind cement raw materials (limestone / clay / iron ore or steel slag / coal ore etc) and cement clinker. Since the media consumption is very low, high chromium grinding media are the best choice for cement plants.

3. Coal-fired power plants
Employed in ball mills or roller mills to grind coal ore, the raw material of power plants.

4. Concrete & construction materials
AAC (autoclaved aerated concrete brick) plants use them to grind raw materials: sand / coal ash;
PHC (pre-stressed high-strength concrete) tubular pile plants use them to grind raw materials;

5. Other industries
High chromium grinding balls also serve the chemical, pharmaceutical, food and fertilizer industries, etc.

Product Applications

How do you pick the right type, size and quantity of grinding media?

1. Match the mill size
Typically, a ball mill with a bigger diameter, fed with larger raw ore and aiming for higher grinding efficiency, calls for large-size grinding cylinders.
At an identical diameter, cylpebs grind more efficiently than balls. So when a small-diameter grinding medium suits your ball mill, cylpebs are the better option over balls.

2. Match the mineral type and the feed & discharge ore size
At a mining processing plant, the first grinding stage uses large-size grinding balls, while the second stage uses small-size grinding balls or cylpebs. High-chromium grinding media bring lower wear cost and high grinding efficiency.
At a cement plant, large-size high-chromium grinding cylpebs go into the first chamber of the cement ball mill, while small-size high chrome grinding cylinders go into the second and third chambers.

3. Size proportioning of the grinding media for the initial charge
For the initial charge, grinding media should make up 35-45% of the total ball mill loading weight, and the media size is chosen according to mill speed, feed mineral size, discharge size and grinding efficiency.