The most common catastrophic mistake made by piping engineers is calculating pump brake horsepower using clear water density (1,000 kg/m³). Slurry power scales directly with slurry mixture density ($S_m$). For an iron ore or copper tailings slurry with $S_m = 1.45$ and an efficiency ratio $ER = 0.88$, the actual power draw is $(1.45 / 0.88) = 1.65 imes$ (65% higher) than water. A motor sized without factoring $S_m$ and $ER$ will trip its overload breakers or catch fire during the first hour of laden slurry commissioning.

Natural rubber liners offer superb abrasion resistance against rounded particles smaller than 5 mm. However, rubber has poor mechanical shear strength at high centrifugal stresses. If a pump speed is cranked up such that impeller peripheral tip speed exceeds 25 to 26 m/s, centrifugal forces and hydrodynamic friction cause rubber delamination, blister formation, and catastrophic tearing from the steel armature. For tip speeds above 26 m/s or sharp-edged angular crushed ore, always specify high-chrome white iron (27% Cr).

Selecting a slurry pump directly from clear water vendor curves without derating by Head Ratio results in the pump delivering less head than required by the discharge pipeline. Coarse slurries can reduce developed head by 10% to 20% ($HR = 0.80 - 0.90$). If the derated slurry curve falls below the pipeline static lift, the flow collapses, velocity drops below the Durand settling limit, and the pipeline immediately sands off, requiring manual dig-out of thousands of meters of pipe.

In mineral flotation circuits, slurries contain frothing reagents and entrained air bubbles (often 5% to 15% air by volume). Centrifugal force inside the rotating impeller separates dense slurry to the outer vane radius while air collects in a stagnant pocket at the impeller eye. This air pocket throttles flow, causes severe surging, reduces head by 40%, and accelerates corrosive cavitation pitting on the vane leading edges. Always specify oversized froth sumps or recessed-impeller froth pumps.

Standard centrifugal slurry pumps use packed stuffing boxes that require external high-pressure gland seal water injected at 35 to 70 kPa (5 to 10 psi) above pump discharge pressure. If gland water pressure drops below internal pump pressure, gritty abrasive slurry enters the packing lantern ring, grinding the hardened shaft sleeve into scrap metal within 48 hours and destroying bearing seals. Always install differential pressure switches with automatic pump trip interlocks.