Copper Slag for Sandblasting

Copper slag is one of the most widely used abrasives for sandblasting steel in India. It is hard, angular, low in free silica and costs far less than garnet or steel grit. This guide explains which copper slag size to use for which job, what surface finish to expect, and how to buy it in bulk.

What is copper slag abrasive?

Copper slag is a glassy, black iron-silicate material formed when copper ore is smelted. When the molten slag is quenched in water, it shatters into sharp, angular granules. Screened into size grades, those granules become a blasting abrasive, covered internationally by ISO 11126-3.

Why blasters choose it

Its hardness of 6 to 7 on the Mohs scale cuts through rust, mill scale and old paint quickly. The angular grains leave a rough anchor profile that helps paint and coatings grip. Free silica is typically below 1%, which makes it a safer replacement for river sand, a material many sites no longer allow for blasting. It is also dense, at around 3.3 to 3.8 specific gravity, so each grain hits hard and the dust settles faster.

Which copper slag size for sandblasting?

• Fine, 0.2 to 0.8 mm: new steel, light rust and thin coatings. Typical profile 40 to 60 microns.

• Medium, 0.5 to 1.5 mm: general structural steel, tanks and pipelines. Typical profile 60 to 85 microns.

• Coarse, 1.0 to 2.5 mm: heavy rust, thick coatings and ship hulls. Typical profile 85 to 120 microns.

A simple rule is to pick the finest grade that still removes the contamination. Finer grains give more impacts per kilo and clean faster. Coarser grains are for heavy scale and deep profiles.

What finish can it achieve?

With dry compressed air at about 6 to 7 bar at the nozzle, copper slag achieves Sa 2.5 (near-white metal) as standard and Sa 3 where needed, as defined in ISO 8501-1. That covers most paint specifications for steel plants, shipyards, bridges, pipelines and power-plant shutdown work.

Can it be reused?

Copper slag is an expendable abrasive. The grains fracture on impact, so it is generally used once in open blasting. For closed blast rooms with recovery systems, steel shot or steel grit works out cheaper over time.

Buying copper slag in bulk

V K Corporation has supplied granulated copper dump slag since 2015, delivered on our own fleet of GPS-tracked trucks across Jharkhand, West Bengal and Odisha, with pan-India dispatch. Material test reports and MSDS are available with every order. Call +91 9234 222 746 or message us on WhatsApp for sizes, samples and rates.