Pulp Density and Percent Solids (Marcy Scale)
Percent solids by weight and the slurry specific gravity a Marcy scale reads, either way.
Example
You enter
- Solids specific gravity (2.7 typical rock) 2.7
- Percent solids by weight (or leave blank and enter the pulp SG) 40
- Measured pulp specific gravity (or leave blank and enter % solids) 0
- Liquid specific gravity (1.0 water) 1
- Dry solids rate (short tons per hour, blank to skip) 100
You get
- Pulp specific gravity 1.337 (11.15 lb/gal)
- Percent solids vol 19.8
- Slurry (GPM) 747.1
No published worked example is on file for this calculation. It is checked against a hand-worked derivation of its method and an independent reference test.
Details, formula, and sources
ScopeFrom the solids specific gravity: 1/SG_pulp = w/SG_s + (1 - w)/SG_water. 40% solids by weight of 2.7 SG rock is a 1.337 SG pulp, only 19.8% solids by volume, and 100 st/h of dry ore at that density needs 150 st/h of water and pumps as about 747 gpm of slurry. Fully wetted solids, no air. A screen; plant sampling governs.
Formula or table1/SG_p = w/SG_s + (1 - w)/SG_l; w = SG_s (SG_p - SG_l)/(SG_p (SG_s - SG_l)); vol % = (w/SG_s)/(w/SG_s + (1 - w)/SG_l); water = Q (1 - w)/w; slurry gpm = (Q/w x 2000/60) / (SG_p x 62.428) x 1728/231.
Source and editionPulp density and percent solids by volume addition (the Marcy-scale relations, as in Wills' Mineral Processing Technology), by name.
Free accessMixture arithmetic on the user's own specific gravities and rates.
What governsEstimate. AHJ and licensed professional govern.
API field namessolids_sg, percent_solids_wt, pulp_sg, liquid_sg, dry_solids_stph, pulp_sg_out, percent_solids_vol, slurry_gpm
- Volume addition solids and liquid volumes add (no air, fully wetted)Wills
- Water density 62.428 lb/ft^3 (8.345 lb/gal)physical constant