Application of Submersible Long Shaft Pumps in Industrial Salt Processing Industry

Long-shaft submersible pumps are widely deployed in brine tanks, settling tanks, salt sludge tanks and mother liquor tanks for industrial salt (sea salt / well and rock salt) processing. Core advantages: the pump head is submerged in brine; no priming required, anti-cavitation. It is mounted above the tank with the motor above the liquid level. Suitable for tank transfer of brine containing salt crystals, salt sludge and high chloride ions. It ranks as one of the main pump types for tank feeding, circulation and mother liquor discharge.

1. Main Application Scenarios

1).Brine tank transfer (most common)Raw brine tanks and refined brine tanks deliver brine to preheating and evaporative crystallization processes. With drastic liquid level fluctuations, long-shaft submersible pumps enable low-liquid-level extraction without foot valves, avoiding cavitation encountered by horizontal centrifugal pumps.

2).Evaporation mother liquor circulation & mother liquor re-extractionFor overflow mother liquor from evaporators and mother liquor collection tanks after centrifugal separation. The nearly saturated mother liquor readily precipitates NaCl crystals. Submersible pumps adopt open / semi-open impellers to allow passage of a small amount of salt crystals.

3).Sludge discharge from salt sludge tanks and clarification tanksSalt sludge and sediment slurry generated from brine settlement is transported to filter presses via anti-corrosion & wear-resistant mortar-type submersible pumps. Note: mortar submersible pumps are preferred for high solid-content salt sludge; ordinary submersible pumps suffer rapid wear.

4).Process wastewater & salt washing wastewater transferWastewater from salt washing sections and saline sewage tanks with high chloride ions and fine salt particles is pumped to neutralization / reuse tanks.

2. Working Condition Characteristics

1).Severe chloride corrosion: Saturated brine contains extremely high chloride ions, with pitting corrosion risks even at ambient temperature; corrosion accelerates at higher temperatures.

2).Blockage by salt crystallization: Saturated / supersaturated brine precipitates salt crystals with slight temperature drops. Crystals adhere to impellers, shaft sleeves and flow passages, locking the rotor.

3).Abrasion by solid content: Brine carries fine sand, salt crystals and salt sludge particles, causing combined damage of corrosion and erosion wear.

3. Material Selection

1).2205 Duplex Stainless Steel (industry first choice): For saturated brine at ambient temperature ~ 80℃. Resists chloride pitting corrosion with good wear resistance, standard configuration for medium and large salt plants.

2).2507 Super Duplex Stainless Steel: For high-temperature saturated brine with many impurities and ultra-high chloride content.

3).316L: Only for low-concentration dilute brine. Not recommended for long-term service in saturated brine due to high risk of pitting penetration.

4).PP / PTFE Lining: For low-temperature dilute brine and wastewater in small & medium plants; not resistant to high temperature or high pressure impact.

5).Seals / rubber components: EPDM, PTFE gaskets. Ordinary NBR nitrile rubber is prohibited, as it quickly ages and swells.