The Role of Dispersants & Process Water in Micronized Calcite Wet Grinding

Why is Dispersant a Critical Input in Wet Milling?

In micronized calcite (calcium carbonate) wet milling cycles, the total surface area increases exponentially as ore grain size decreases to micron and submicron levels (e.g. d₅₀ / d₉₇ targets). Due to the attractive forces between fine calcite particles, the viscosity of the suspension (slurry) increases rapidly, the fluidity decreases and the grinding efficiency in ball/stirred mills decreases. The dispersant creates electrostatic and steric repulsion by adhering to the surface of calcite particles; Thus, it helps to obtain a fluid suspension even at high solid rates. Elif Çevre Kimya offers low molecular weight sodium/ammonium polyacrylate dispersants among its product groups on its mineral and calcite sector page.

Process Water is a Direct Part of Chemical Selection

The same dispersant may not give the same viscosity curve in different process waters. The hardness (calcium and magnesium ions), conductivity, pH of the water used in wet grinding and the amount of residual flocculant contained in the water returning from the thickener directly change the charge balance on the particle surface. Therefore, it is necessary to monitor process water as an active component of the grinding recipe rather than seeing it only as a carrier liquid. Additionally, stearic acid surface coating agents and thickener water recovery flocculants (A-PAM) available on the site belong to different process steps; The place of duty of each should be evaluated separately.

Laboratory Rheology Testing and Field Verification

Before product selection, Brookfield viscosity, sedimentation stability and grain size distribution experiments should be carried out in the laboratory with the facility's own calcite ore and its own process water at different solid ratios. Constant dosing or energy savings cannot be guaranteed unless the mill temperature and gradual dosing points are verified in the field.

Field Control and Monitoring List

Chemical dosage and system capacity decisions should be determined by analysis and facility conditions; There is no guarantee of fixed dosage or performance.

• Analysis of hardness, conductivity and thickener return water ratio of wet grinding feed water
• Creating the viscosity-dosage curve with the facility's own calcite sample at the target solid ratio (65–78%)
• Control of the feed distribution of the dispersant between the mill inlet and stages
• Monitoring the sedimentation stability of the post-grinding suspension in storage tanks
• Verification of yellowing/foaming compatibility for the industry (paint, paper, plastic) in which the final product will be used