SZBQ Submersible Slurry Pump

Overview

The SZBQ range is a fully submerged pump-and-motor unit for abrasive solids in mining, metallurgy, power generation, coal handling, river and lake dredging and sand extraction. Because the unit sits directly in the sump, no pump house, foundation or suction pipework is required, which removes the civil works normally needed for a dry-installed set. Typical media are coal slime, iron oxide, mineral concentrate, ash, silt and gravel at up to 70 degrees C.

Working conditions

Model designation

Example: 65SZBQ(G)-30-15-7.5

Model numbers in the performance table below are printed in the SZ(B)Q form used on our factory data sheets; the two are the same designation.

Duty Envelope and Wet-End Materials

Flow reaches 25–5,500 m³/h against 9–135 m of head, with motors from 4 to 630 kW, bore 50–600 mm. Solids are accepted to 60% by weight (45% for mortar), specific gravity to 1.3, immersion to the seal design depth of 2 m, at pH 8. Wet parts are cast in 27% chrome A05 alloy for abrasion and mild corrosion.

The pump handles media carrying solid particles such as mineral powder, ash, iron oxide, coal slime, sediment and gravel. Solids concentration by weight reaches 45 % for mortar and 60 % for pulp. Particle size must not exceed 80 % of the smallest flow-passage dimension of the selected pump. For medium above the standard temperature range, specify in advance so that the unit can be built accordingly.

Sealing and Motor Protection

Two tungsten-carbide mechanical seals run in series with an oil chamber between them: the outer seal faces the slurry, the inner seal keeps oil out of the motor, and the chamber acts as a buffer if the outer seal is breached. Seal service life reaches 30,000 hours. The motor is IP68 with class F insulation, a 4-pole IE3 stator on 600-grade silicon steel, a Q235 shell with 316 fasteners and a tempered 4Cr13 shaft. An oil-water probe, float switch and winding thermistor feed a PLC display that alarms and stops the set on leakage, overload, phase loss, short circuit or bearing over-temperature.

The motor shaft is sealed by two independent mechanical seals in series with tungsten carbide friction pairs. The first runs in the pumped medium and tightens as medium pressure rises; the second runs in the oil chamber and prevents oil reaching the motor. The oil chamber lubricates and cools both seal faces and carries away bearing heat. Under normal service, trouble-free running of this arrangement exceeds 15,000 hours, and the seal set is designed around a 2 m seal submergence.

Protection and Monitoring

Submersible motor life is normally limited by how the motor fails rather than how it wears: dry running, seal leakage admitting medium into the windings, or sustained overload raising winding temperature. The SZBQ package monitors each of these directly.

• Winding over-temperature — thermal elements embedded in the stator winding raise an alarm and stop the pump when winding temperature reaches the set point.
• Oil-chamber leakage probe — detects failure of the primary mechanical seal and signals when leaked medium reaches a set proportion in the oil chamber.
• Motor-cavity float switch — detects failure of the secondary seal; when oil or an oil-water mixture reaches the motor cavity the pump is stopped.
• Bearing temperature — monitors motor bearing temperature.
• Electrical protection — overload, phase loss and short-circuit protection.

Signals are processed in a dedicated control panel providing control, protection, audible and visual alarm, and single- or multi-pump automatic sequencing. Where the customer supplies their own panel, the protection controller must be fitted in that panel; our electrical group will advise on the installation.

Motor and Electrical Construction

• Purpose-designed submersible motor, IP68 enclosure, class F insulation.
• Motor shell in Q235 steel with 316 stainless fasteners.
• Stator and rotor in 600-grade silicon steel; windings in Q2T/180 high-temperature magnet wire; motor efficiency class 2.
• Motor shaft in 4Cr13, tempered.
• Bearings: double-row angular contact bearing at the lower position with a deep-groove bearing above, sized with margin for the radial and axial loads of solids-handling duty.
• Heavy-duty rubber-sheathed flexible cable rated for continuous full-load operation at 40 °C ambient; cable gland compressed against the motor cover, with rubber vulcanised to the conductor cores so that a damaged outer sheath still does not admit medium to the motor.

Motor heat is rejected through the stator casing into the surrounding liquid. Reliable operation requires only that the stator casing remains submerged; cooling improves as submergence increases. In falling-level dewatering, minimum immersion must therefore be maintained — specify run-dry sensing where the level can drop below the motor.

Agitator Arrangements

• Mixing wheel — mounted at the bottom of the pump, it turns settled sludge into a moving suspension for extraction. The unit combines submerged operation, agitation, sand loosening and sand pumping in one assembly.
• External agitator / cutter — for compacted or hardened deposits, an external agitator with cutting action breaks the material down before it reaches the impeller.
• Mixing blade extension — on SSP/SSPR vertical units a mixing blade is carried on the extension of the impeller suction side, serving the same purpose in settling-pond duty.

Casing and impeller are cast in high-chrome wear-resistant, corrosion-resistant alloy (A05). The impeller and casing are matched on test so that the power curve stays flat and the unit is not easily overloaded when solids loading changes. Impellers are balanced to keep vibration low, which matters in agitator duty where inlet loading is intermittent by nature.

Installation Arrangements

• Fixed installation — quick-fit guide-rail components are anchored to the foundation. When service is due the pump is lifted along the rail by chain; on lowering it re-connects automatically to the quick-fit discharge elbow. The sump does not have to be drained to remove the pump.
• Mobile installation — the pump is moved between sumps as required, with no fixed civil work.

Automatic Control

Four control configurations are available and are selected against the duty: standard water supply and drainage; supply and drainage with overflow alarm; continuous automatic alternating drainage; and continuous automatic alternating drainage with overflow alarm. The alternating configurations suit duty and standby sets that must share running hours, and the overflow alarm configurations suit sumps where a rising level must raise an alarm rather than simply flood.

Electrical control can be specified for 380–600 V and 50 or 60 Hz. PLC display monitoring covers bearing temperature, seal leakage, motor water ingress and motor overcurrent or overheating, with live status readout.

Maintenance and Service Intervals

• Check running current against rated current on each inspection; a persistent deviation indicates a developing overload.
• Confirm cooling flow past the motor casing and that minimum immersion is maintained.
• Renew mechanical seals at 4,000 hours; set impeller clearance to 0.5–1 mm.
• Relubricate bearings with NLGI #3 grease at 2,000-hour intervals.
• Take an oil sample at 2,000-hour intervals to detect seal or bearing wear.
• Flush with clean water for 20 minutes after operation to clear abrasive residue.
• For long shutdown, store drained with anti-corrosion treatment applied.

• Vibration rising above 7.1 mm/s indicates impeller imbalance — rebalance or replace the impeller.
• A falling duty point at unchanged speed indicates wear-ring and clearance loss — renew the wear parts.
• Avoid dry running; it is the most common cause of submersible motor failure.

Typical Applications

• Mining and metallurgy — tailings disposal and abrasive slurry transfer in mineral processing.
• Power generation — fly ash, bottom ash and desulphurisation sludge.
• Dredging and environmental works — river desilting and harbour maintenance.
• Municipal and construction — sump dewatering, sediment and flowing sand.
• Coal, cement and paper — mortar, pulp and high-solids slurries.
• Construction excavation and tunnelling dewatering.
• Municipal drainage sumps and stormwater pits carrying sediment.
• Settling ponds and thickener underflow where solids consolidate at the floor.

Selection

Send the required flow, head, medium, particle size, solids concentration, density, voltage and frequency. We will confirm the model, wet-end material and control configuration, and issue the matching performance curve with the quotation.

If settled material at the sump floor is part of the problem, tell us how consolidated it is and we will confirm whether a mixing wheel or an external cutter agitator suits the duty.

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