GM-1: High Chrome Cast Grinding Ball for Ball Mill / SAG Mill / Tower Mill

Key Advantages

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

Greater hardness
After special heat treatment (Oil quench & annealing), High Chromium cast balls are harder than forged grinding balls. A 10% Cr- Chromium cast ball with a diameter of Φ10 - Φ70 mm can reach a hardness of HRC 66, far above forged balls and low-chrome steel balls. The hardness difference between ball surface and core is also under HRC 1.

Tailored alloy steel composition
To meet customer requirements, the NGZR foundry can adjust the Chromium alloy content (1.0-28%) of the chemical composition, along with other metallic elements. Together with special heat treatment, this gives the cast steel balls 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 differing 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 chromium cast grinding balls have good physical properties. Large cast balls show a breakage & out-of-roundness rate below 1%, and small cast balls show one below 0.5%.

Applications

High chromium cast grinding balls are consumable grinding media. Ball mills, SAG mills, AG mills, tower mills, roller mills and vertical mills use them to mill 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
Generally, a mill with a bigger diameter, fed with larger raw ore and aiming for higher grinding efficiency, calls for a large-size grinding ball. Once the mill diameter exceeds 6 meters, grinding balls break more often; select a high-toughness grinding ball, which means your grinding media supplier must manufacture it specially for you.

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

3. Size proportioning of the grinding media for the initial charge
At the first installation of a ball mill, grinding balls should make up 35-45% of the total ball mill loading weight, and the grinding media loading weight is adjusted according to mill speed, feed mineral size, discharge size and grinding efficiency. The initial charge holds 3-5 grinding ball sizes, with middle-size balls above 50% of the quantity; after that, large-size balls are added in line with grinding media consumption.