GRINDING MEDIA KNOWLEDGE
How to Write a Grinding Ball Purchase Specification
Define mill duty, product requirements, inspection and commercial terms for comparable grinding media bids.
Start with the operating duty
State the mill type, diameter, speed, liner design, wet or dry operation, ore or clinker type, feed and product size, current media size mix and consumption. Without this context, suppliers may quote the same nominal ball for very different impact, abrasion and corrosion conditions.
Define measurable product requirements
List diameters and quantities, manufacturing route, agreed chemistry range, surface and core hardness, hardness uniformity, dimensional tolerance, roundness and permitted surface defects. Avoid copying one supplier’s proprietary grade name; use performance and testable characteristics that all qualified bidders can address.
Set sampling and acceptance rules
Specify batch identity, sampling frequency, laboratory methods, impact or drop tests, breakage limits and the documents required with shipment. Describe how nonconforming lots will be quarantined, retested or replaced. Retain samples and records so any complaint can be linked to a traceable heat or batch.
Make commercial offers comparable
Require bidders to use the same Incoterm, destination, currency, packaging, payload assumptions, lead time and payment basis. Ask separately for unit price, freight and optional testing. Evaluate delivered cost per tonne of ore, trial performance and supply reliability—not only price per tonne of balls.