Overview of modern slurry pumps
In connection with the widespread use of enrichment schemes based on the use of a large amount of water at the processing plants of the mining and mining and chemical industries of the national economy, the issue of the correct choice of pumping equipment is one of the key ones both technically and commercially.
Of the many types of pumps, special attention of manufacturers and designers is attracted by slurry pumps operating with medium and high abrasiveness (in crushing process lines, after mills of the first and second stages of grinding, during high-pressure transportation of concentrates and tailings of processing plants, etc.). The pumping of such materials is associated with relatively rapid wear of individual parts of pulp pumps, their repair and replacement. The operation of such pumps is accompanied by high energy costs and requires reliable sealing of the space between the cantilever part of the shaft and the pump housing.
The characteristic operating conditions of a modern pulp centrifugal pump can be taken as a pulp flow rate in the range from 10 to 10 thousand m 3 / hour, a pressure in the range from 10 to 100 m of water. Art. and the density of the pulp from barely exceeding the density of water to 2.0 t/m 3 .
This article is devoted to an overview of modern single-stage centrifugal slurry pumps (hereinafter referred to as pumps) operating with abrasive media at Russian enterprises under the above conditions. The pumps of the largest manufacturing companies are briefly considered, as well as certain technical issues of the features of their operation and choice.
The modern industry imposes on pumps in many respects the same requirements as decades ago. First of all, these are high reliability, wear resistance and economical consumption of electricity during operation, cost reduction during repair and operation, economic efficiency, etc. At the same time, modern enterprises are increasingly paying attention to the fact that high reliability and wear resistance characterize the operation of pumps in increasingly difficult operating conditions, i.e. at high pulp pressure and high consumption of abrasive medium, while the total number of operating pumps decreases. .
In response to market needs, modern machine-building companies that produce pumps offer a fairly wide range of equipment, characterized by certain features.
To assess the features of pumping equipment offered to the Russian market by various companies, we briefly list some of the characteristic features of pumps.
According to the spatial arrangement of the shaft on which the impeller of the pump is located, it is generally accepted to subdivide the pumps into horizontal and vertical.
Depending on the location of the housing relative to the surface of the pulp, the pumps are divided into surface and submersible. Separately, semi-submersible units are distinguished, in which the pump is located under the level of the pulp, and the engine is above it.
The main features that characterize the geometric dimensions and, accordingly, the nominal performance of the pumps are the diameters of their suction and discharge pipes, as well as the diameter of the impeller. The main feature can be taken as the diameter of the discharge pipe, which is currently in the range from 25 to 800 mm.
At present, horizontal pumps are predominantly used for heavy duty applications. Submersible and semi-submersible pumps mainly work with a slurry containing a relatively small amount of solid particles (drainage water, suspension from metallurgical enterprises, etc.).
Pumps of the Bobruisk machine-building plant
For well-known historical reasons, the most common horizontal surface pumps at the enterprises of Russia and the CIS countries continue to be pumps manufactured by the Bobruisk Machine-Building Plant (Belarus). As previously at the enterprises of the USSR, these pumps are used both in the lightest and in the most difficult operating conditions. For example, at the tailings of the iron ore production of the Kachkanar GOK, Bobruisk pumps have been operating for many years on slurry with a nominal flow rate of 8000 m 3 /hour, a nominal head of 71 m of water. Art. and a pulp density of about 1100 kg/m 3 .
The Bobruisk Machine-Building Plant declares that the pumps of the GrA, GraU, GrT and other types produced by it are designed for pumping abrasive slurries with a density of up to 1600 kg / m 3, a temperature of up to 70 ° C, a maximum size of solid inclusions up to 25 mm and a volume %. The wet end can be made of superhard alloys, organic bonded abrasive material, rubber and polyurethane.
An attractive feature of Bobruisk pumps is their relatively low price. However, in terms of reliability, durability and efficiency, they do not always compete with the best foreign analogues.
Metso Minerals pumps
A major foreign company producing pumping equipment is Metso Minerals , which previously supplied pumps as Svedala . From Metso Minerals' large family of slurry pumps, heavy duty pumps are the X series, while medium and light duty pumps are the H and M series pumps, which are available with both rubber lined and metal inner casings and are referred to as XR, XM types, respectively. , HR, HM, MR and MM. H-series pumps are available with suction nozzle diameters up to 350-400 mm, and X-series pumps (XM, XR), designed for extra heavy duty applications, from 350 mm and above. The hydraulic design of the X series pumps is based on the Thomas design, while the H series pumps are based on the Orion design.
Separately, it is worth dwelling on Metso Minerals vertical semi-submersible pumps. These pumps of the VT and VF series, although they operate in a relatively small range of heads (up to a maximum of 45 m w.c.) and flow rates (up to a maximum of 1500 m 3 / h), but due to their design (long cantilever shaft, suction from the shaft side) do not have the shaft seal assembly and associated problems typical of horizontal pumps.
Standard wear parts are made of natural rubber (Elastaslide, etc.) or hard alloys (Metachrome, Metahard, Metalsize, etc.), as well as synthetic rubber and rubber. Pumps manufactured by Metso Minerals in Russia are equipped, for example, at the processing plant in Nyurbinsky GOK (AK ALROSA) and the processing plant "Nelkobazoloto".
Krebs pumps
A large foreign pumping company actively entering the Russian market is the American company Krebs , previously widely known only as a leader in the production of hydrocyclones. A distinctive feature of the Krebs pumps is the new patented design of the suction section of the pump, which significantly reduces the internal recirculation inside the pump flow path. According to the manufacturer, the new design provides:
less intense and more uniform wear of parts of the flow path
maintaining the pressure developed by the pump at a constant level
reduction of electricity consumption by 10–25%
reduction of material and labor costs for operation and repair
The Krebs millMAX pump has a cast metal casing and a metal impeller, while the SlariMAX pump has a rubber casing lining and a metal impeller. Metal parts are made from high-chromium alloys called Krebsalla, rubber parts are made from natural rubber. In a short time, MillMAKS pumps have become widespread in the West. On the territory of Russia, a new coal preparation plant in Mezhdurechensk is equipped with Krebs millMAKS pumps.
Krebs pumps are primarily designed for heavy duty applications. In medium and light conditions, the above advantages of the design are not so obvious and do not reveal themselves so quickly.
GIW pumps
In the West, the pumps of the GI Double U ( GIW ) company, which is currently part of the KSB company ( KSB ), are quite widespread . The pumps have a wide range of applications and are labeled LCC, LCV, LSA, LSR, MEGA and WBC.
For example, the company's LCC-M pumps have a single-casing design, use high-strength Gasite material for wear parts, have discharge sizes up to 12 inches, flow rates up to 3865 m 3 / hour and head up to 90 m of water. Art. (subtype of these pumps LCC-H is declared for head up to 107 m w.c.). LCC-R pumps are rubber lined, have discharge sizes up to 12 inches, flow rates up to 2260 m 3 /h and heads up to 45 m w.c. Art. It is possible to manufacture impellers from polyurethane.
LSA pumps at a plant in Chile are running after the first grinding stage with a flow rate of up to 8600 m 3 /h and a drive of 1860 kW.
In the Russian market, the pumps of this company are not yet widely known.
Pumps from other companies
In addition to the above companies, there are others that produce pumps for both medium and low abrasive material, as well as for certain severe conditions.
Thus, Habermann pumps designed for pumping highly abrasive slurries and sandy particles are marked NP and NPK, and for pumping large, including gravel particles up to 100 or more millimeters - KB and KVR. The HBN450VG material used for the metal parts of these pumps has a Brinell hardness of 650. The pumps of this company are not yet typical for the Russian market. Under medium abrasive operating conditions at the Pechenganickel concentrator, pumps from the Finnish company Zulser , formerly manufactured by Ahlstrom , and having a Selakius hydraulic design, successfully operate.
Submersible pumps from CNZKING have been used for drainage water and pumping inside process water enterprises in Russia and abroad .
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