Hydroabrasive Wear Research Articles

Study on agitator resistance to hydroabrasive wear

Resistance of structural materials used in the mining industry to hydroabrasive wear is one of the key factors for the durability of many mechanisms, especially agitators. When mixing concentrated slurries, rotating agitator elements interact with suspended abrasive particles of the rock. Inadequate selection of structural materials for these elements causes frequent replacements due to hydroabrasive wear and related process shutdowns. Hydroabrasive wear by solid particles occurs as a result of cyclic impacts of fine solid particles entrained in a gas or liquid flow and striking the surface of a solid body. The mechanical action of these particles is similar to abrasion and includes plastic deformation and brittle fracture. In addition to hydroabrasive wear, exposure to chemicals leads to corrosive wear. Material resistance to corrosion depends on many factors related to both the material and the corrosive solution. This paper presents the results of a study of resistance of various materials to hydroabrasive wear in a corrosive and abrasive environment. Samples made in the form of 3–4 mm thick rectangular plates were selected for the study. St3sp and 12Kh18N10T grade steels were used, as well as a composite material consisting of glass fiber and polymer binders. The test results show that resistance of the composite material is much superior to that of metal samples. This is mainly due to the inertness of polymeric materials to corrosion.

Determined to the microstructural and mechanical properties of deposits made of high alloy steels used in the construction of environmentally friendly hydraulic turbines

Research on hydraulic turbines, regardless of type, has shown that all materials used in the manufacture of parts that are components of the flow path, working in the same conditions, are subject to hydro-abrasive wear, in different proportions. The most attacked components are the blades and the chambers of the hydraulic turbines. In this paper are studied materials used in the construction of hydraulic turbine blades that have been previously deposited by the method of the electro-spark deposition with tungsten carbide (WC) electrodes. These deposits were made in order to offer the turbine blades as high a reliability as possible but also to be able to use such hydraulic turbines in the harshest conditions and which could provide as much energy as possible. A high-alloy stainless steel containing Cr and Ni was used as the basic material for the study. The raw samples from a hydraulic turbine blade and those submitted were analyzed both structurally using the optical stereomicroscope and the SEM electron microscope and chemically using the EDX probe. High alloy steel based on Cr and Ni but also WC deposits will be subjected to mechanical tests to see how they resist wear.

Оценка степени влияния твердой фазы шахтных вод на долговечность узла гидравлической пяты секционного насоса главной водоотливной установки рудника «Удачный»

Introduction. The main factors, which negatively influence on durability of balancing ring of sectional pump, are presented. Object of study. The sectional pumps of the dewatering facilities of the kimberlite mine “Udachny”. The purpose of the research. Assessment of the mine waters solid phase influence degree on balancing ring durability of sectional pump to clarify the expected technical and economic effect of penetration of an additional clarifying tank in the conditions of the main drainage of the kimberlite mine “Udachny”. Research methodology.The results of inspections of the failed balancing rings allowed to establish the main types of their damage. Next, according to the results of analytical researches main factors were determined, which are accompanied with loss of operability of balancing ring. Then, with the help of correlation and regression analysis degree of influence of each of the factors on the durability of balancing ring was estimated. Research results. According to the visual inspection, the hydroabrasive wear is most strongly manifested in places of contact friction of parts of the balancing ring unit.It has been found that the life of the balancing ring unit of the sectional pump with the smooth start of a separately taken water drainage plant can be calculated as a linear function of the conditional intensity of the hydro-abrasive-adhesive wear of its parts, which is the product of the concentration of mechanical impurities in the mine waters and the wear resistance coefficient of the metal, which takes into account the total operating time of the pump in transient modes. In the underground development of kimberlite ores, the service life of the balancing ring unit is primarily determined by the pressure developed by the sectional pump. At the kimberlite mine “Udachny” of PJSC ALROSA, where there is a maximum concentration of mechanical impurities in the mine waters under the conditions of the main water drainage, the additional clarifying reservoir is driven by a useful volume, which significantly exceeds the operating water-collecting mining workings.The inclusion of this clarifying tank in the current process chain for clarifying mine waters will significantly reduce the content of solid phase in them, which in theory should positively affect the durability of the components of the flow part of the pumping equipment, including the balancing ring unit.

System analysis of internal and external impacts on overhaul repair frequency of vertical split casing pumps

ALROSA is currently starting transition from surface to underground mining of kimberlite pipes. Underground mining promotes with various-nature rushes of water in underground openings. These inflows of water are finally collected in drain sumps of the main water-removal plant, and then are pumped out to ground surface by vertical split casing pumps. The practice shows that frequent overhaul repairs are typical of the domestic-manufacture split casing pumps operated in underground kimberlite mines. The overhaul repair frequency of the vertical split casing pumps is largely governed by the radial clearance between the inside faces of the gasket rings and the outside surfaces of the seal bands of the impellers. It is found that the dominant impact on the multifactor damage pattern of impeller sealers in vertical split casing pumps operated in underground kimberlite mines in Russia is exerted by hydro-abrasive wear, especially at the sites of corrosive filming. The integrated research finds out that the average service life between the overhaul repairs of the vertical split casing pumps in use in the underground kimberlite mines in Russia greatly depends on such external and internal impacts as the pump head, error-free running time of the balancing ring and concentration of mechanical impurities in mine water. The implemented regression analysis has yielded a prognostic model which allows a sufficiently reliable perspective forecast of average service life of the vertical split casing pumps between overhaul repairs for the underground kimberlite mines in Yakutia.

Effect of electrochemical treatment on substrate adhesion strength in the restoration of motor vehicle parts operating under hydroabrasive wear

Introduction. In the process of chrome plating of car parts, it is necessary to obtain high-quality chrome coatings with specified physical and mechanical properties. Therefore, electrochemical treatment before coating plays a crucial role in the formation of coatings with high contact strength and wear resistance. The study of the electrochemical treatment process will make it possible to develop recommendations for obtaining high-quality coatings when restoring vehicle parts.Materials and methods. To conduct reliable research, the necessary equipment was used, which made it possible to obtain data with the necessary accuracy. Also, modern data processing tools were used to carry out mathematical processing, which excluded the possibility of error and thereby obtain the dependences of factors with the necessary accuracy.Results. When using the developed new chromium plating electrolyte, it became necessary to conduct studies of the modes and time of electrochemical treatment before coating parts made of steels containing chromium and hardened to HRC 55-60 hardness. Based on the results obtained, it was found that the greatest adhesion strength will be when using electrochemical etching with a current density of 130-140 A/dm2 and a holding time of 60-70 s. It is also necessary to activate in the chrome plating solution itself with an anode current density of 70-80 A/dm2 and a time of 30-40 s, with a sharp switch to the chrome plating mode. Conclusions are drawn on the optimization of electrochemical surface treatment before chrome plating, in order to obtain the greatest adhesion to the substrate. Discussion and conclusion. As a result of the conducted studies of the electrochemical processing of the part before chrome plating, it was possible to obtain that when restoring parts operating under waterjet wear, it is necessary to observe the specified conditions for obtaining high-quality coatings with high adhesion strength while maintaining high physical and mechanical properties of the coating.

On the effects of cavitation on the operation of slurry pumps

Low operational reliability is characteristic of the pumping equipment (domestic and foreign slurry pumps) at all processing plants, the bearing assembly being one of their least reliable elements. Bearing failure can account for up to half of all slurry pump downtime. Heavy loading is the main cause of premature bearing failure and is caused, in most cases, by an imbalance of the impeller developing due to abrasion by suspended solids, which may be evidenced by an increase in the centrifugal force of inertia. In practice, in addition to intensive hydroabrasive wear of the impeller, shock waves resulting from the collapse of cavitation cavities also contribute to higher centrifugal forces of inertia when pumping abrasive slurries. The development of cavitation in pumps at processing plants is explained by the throttling of the pump suction line in order to ensure the required performance. This article assesses the consequences of slurry pump operation in cavitation conditions for the vibration characteristics of its parts and assemblies. In respective experimental studies, certain regularities have been identified behind the variations of the rootmean-square value (RMS) of the vibration velocity of a pump (similar to a slurry pump) depending on the performance controlled by throttling the suction line. It has been established that suction line throttling can additionally increase the RMS of the vibration velocity for the bearings of pumping equipment at processing plants by 10–15 %. The results of this research will be useful to pumping equipment operators at mining enterprises.

Specific pressure loss calculations for tailings hydrotransport at the Kachkanar GOK

Mining transportation systems are evolving through the introduction of continuous transportation solutions, hydraulic pipeline transport being the most common of them. Considering the high labor and energy intensity of equipment operation, accelerated hydroabrasive wear of pipelines, and elevated metal consumption, respective mining hydrotransport efficiency assessments indicate a significant streamlining potential. Energy intensity of any transportation process depends on the specific head loss Icm and the concentration of the solid phase. Lower pressure losses and higher concentrations reduce the energy requirements for pumping a given volume of solid materials (tailings) and, consequently, improve the resulting hydraulic transport efficiency. The purpose of this work was to establish the change patterns for specific head losses at varying solid phase concentrations in the flow during hydraulic transportation of overflow hydrocycloning products via 800–1000 mm metal pipes with a mass fraction of the solid phase of 17 % (±5 %), as well as to develop recommendations for the design of tailing facilities of the Kachkanar GOK. The experiments conducted have established that specific head losses are directly proportional to concentrations of the solid phase in the tailings slurry. Higher solid phase concentrations and hydrotransport system throughput lead to increased pressure losses. This happens because elevated solid phase concentrations trigger the manifestation of rheological properties of the slurry in the liquid flow, affecting the specific head loss. The research results obtained are reflected in the reconstruction and development design for the plant.

Modeling and Simulation of the Erosion Rate in Hydraulic Structures

Basically, the durability of hydraulic structures is heavily influenced by concrete surface resistance against mechanical wear. Hydro-abrasion is the term used to describe deterioration of concrete surface inflicted by the continuous removal of surface material due to the effect of water-dragged solids. This type of cumulative damage for the surface of concrete may be seen in practically all hydraulic systems, in varying degrees of severity. Essentially, such hydro-abrasive concrete wear reduces the life span of the hydraulic structure, and as a result of the maintenance necessary, the facility's non-operation during the repair time increases costs. The impact employed by the flow inclination angle, density (sand concentration in water), and velocity were studied in this work. The three various angles (30°, 45°, and 60°) different densities (35 and 45 kg/m3), and different velocities of 600, 900, and 1200 rpm were numerically determined using the program of ANSYS and the discrete phase model (DPM) for simulating the fluid solids. According to the directed numerical simulation, the greatest rate of erosion was observed when the inclination angle of the flowing water was 60°, while the least value was obtained when the inclination angle of flow was 45°, in addition, the erosion rate increases as the density and velocity increases.

Investigation of Ti/TiB2 Composite Wear Resistance and Corrosion Resistance Coatings in Aggressive Medium and at Variable Temperatures

The present work investigates the influence of conditions like the climate of the Arctic shelf, such as aggressive medium, hydroabrasive wear and variable temperatures on Ti/TiB2 composite coatings. The applicable composite powders were investigated with the use of thermogravimetric analysis. The values of corrosion resistance and wear resistance of the coatings were also investigated.

The Structure and Characteristics of Wear-Resistant Coatings, Obtained by Supersonic Plasma Spraying

The characteristics of coatings designed to protect against cavitation and waterjet wear, obtained by supersonic atmospheric plasma spraying using air as a plasma-forming gas, are studied. The following powder materials were selected for coating: WC/10Co4Cr; Ni-Cr-B-Si-C; Ni-Al; Ni-Ti; bronze. Metallographic studies of the structures of specimens with applied coatings and measurements of their microhardness were carried out. Due to the fact that the tests of materials for hydroabrasive wear are not standardized, studies were carried out on the resistance of coatings to dry abrasive wear according to the ASTM G65-04 standard and to dry reciprocating friction according to the ASTM G133 standard. The conducted studies of the structures of the sprayed coatings suggest that the use of supersonic deposition modes guarantees the production of high-density coatings with a porosity of less than 1 %.

Influence of structure and mechanical properties on hydroabrasive wear resistance of cast Iron

Results of study of hydro abrasive wear resistance of unalloyed and micro alloyed Sn and Sb cast irons with different forms of graphite and metal base structure are presented. It is shown that high-strength ductile cast iron with spherical graphite andpearlitic-ferritic base (P70) with high ductility and high impact toughness has the greatest resistance to hydro abrasive wear.

Increasing the Time between Failures of Electric Submersible Pumps for Oil Production with High Content of Mechanical Impurities

The main principles of hydroabrasive wear of parts of the pumping stages of well’s electric submersible pumps are considered in this article. The concentration, grain-size distribution and shape of solid particles have the greatest impact on the abrasion ability of particles of mechanical impurities interacting with the parts of pumping equipment. The implementation of filters is the most effective and affordable way to protect borehole electric submersible pumps from hydroabrasive wear. Filters reduce the concentration and decrease the average grain-size of mechanical impurities going through the pumping stages. The authors propose variants of constructive and schematic solutions of self-cleaning slot filters, providing an increase in the operating time of electric centrifugal pump units during production of well fluid with a high content of mechanical impurities. The operating principle of the proposed filters is described. The results of calculations of deformation of tubing string during the increase in pressure at the oil wellhead are presented, confirming the possibility of restoring the permeability of spring filter elements without lifting the pump unit to the surface.

On the causes of slurry pump failures in the processing of diamond sands and ores (review)

Hydraulic transportation units, namely, Russian and foreign-made slurry pumps, form an important link in the process chains for the processing of diamond-bearing mineral raw materials operated at such Russian mining companies as «Almazy Anabara» and «ALROSA». Despite their criticality, slurry pumps at the processing facilities of these companies are generally operated inefficiently and are unreliable. Low availability of the slurry pumps at «ALROSA» processing plants is due to the frequent failures of their wet end parts and, to a lesser extent, to the failures of bearings, shafts, and seals. Slurry pump downtime at the screening plants of «Almazy Anabara» mines is mainly caused by impeller failures. The abrasive slurry pumped in the process is the leading cause of malfunctions of the above-mentioned parts, which has been confirmed by relevant statistical studies. It has been established that durability of wet end parts in the slurry pumps of «ALROSA» concentrators, determined as their hydroabrasive wear resistance, largely depends on the wear resistance of the material of the part itself, the density of the slurry pumped, and the coefficient for the pump shaft rpm. The wear life of impellers in the slurry pumps at the screening plants of «Almazy Anabara» mines depends on the wear resistance coefficient of the impeller material and on the grainsize composition of the solid phase of the slurry pumped.

Mechanized complex of mine water purification from large mechanical impurities

It is well known that the main reason for the failure of sectional pumps in underground mines is the extensive hydroabrasive wear of their impellers. The rate of hydroabrasive wear of the impellers of sectional pumps largely depends on the size of solid particles contained in mine waters. Within the framework of this research work, in order to reduce the rate of hydroabrasive wear of parts of the flow path of sectional pumps of mine drainage installations, in particular impellers, a mechanized complex was developed and sufficiently substantiated for cleaning mine water from large solid particles. It is based on the use of a hydrocyclone and a high-frequency screen. Introduction of the developed technical solution in mine drainage systems will reduce the intensity of hydroabrasive wear of sectional pump impellers.

The variations of wear readings study according to EN 295-3 method using the ISO 6133 standard for analysis of multi-peak curves

It is shown that the set of data on the loss of wall thickness when determining the magnitude of hydroabrasive wear is a multipeak curve. An attempt was made to determine the amount of wear in accordance with the requirements of ISO 6133 "Analysis of multipeak traces". It has been shown that this treatment reveals higher wear values than those applied according to EN 295-3.

Experimental hydrotransportation unit for testing material resistance of pipelines and parts of dredging pumps to hydroabrasive wear

The paper analyzes the existing standardized Russian and international methods for testing the resistance of materials to abrasive wear. According to the results, it has been found that only one of the five methods enables direct hydroabrasive wear testing for pipelines. The authors have developed a technique for the experimental measurement of the intensity of hydroabrasive wear of coating materials for pipelines and parts of dredging pumps, head losses, and the reduction in energy efficiency depending on the roughness, operation time of the slurry pipes, concentration of the solid phase of the slurry, average speed and volume of the solid material transported. Based on this technique, an experimental hydrotransportation unit was designed and assembled to test the wear resistance of materials of hydrotransportation systems. The hydrotransportation process implemented using the unit in laboratory conditions is as close as possible to the actual operating conditions at mining and processing enterprises. A pipeline system, an impeller, a pump housing, and other flow parts of a hydrotransportation unit made of various materials may be used as research objects. The experimental hydrotransportation unit allows testing the wear resistance of samples of pipes and linings of pipelines, pump parts (impeller, housing) made of various materials, such as steel, cast iron, plastic, polyurethane, rubber, etc.

On the streamlined service life of impellers of gravel pumps in the beneficiation of diamondiferous sands

Loss of gravel pump operability in a dense-medium unit (DMU) due to extensive hydroabrasive wear of the impeller is currently among the key causes for the screening plant downtime at the mines of «Almazy Anabara» JSC (Yakutia), reducing their diamondiferous sands washing output. It usually takes up to two hours to replace a broken pump with a backup unit. According to the calculations, each forced downtime of a screening plant due to a DMU gravel pump replacement can lead to losses of around one million rubles. In order to reduce this downtime, all gravel pumps at «Almazy Anabara» mines were additionally equipped with frequency converters, maintaining the operating pressure in the dense-medium hydrocyclone despite the gradual deterioration of the impeller due to attrition by the slurry solid phase. However, the converters prevent the complete utilization of the impeller service life in gravel pumps. At the time of decommissioning, the rpm of gravel pump electric motors exceeds the nominal values by 8–15 %. This variation is due to the lack of recommendations for the maximum possible increase in the number of revolutions. The purpose of this work is to substantiate a streamlined service life for DMU gravel pumps to enable more efficient utilization of the process equipment of screening plants at the mines of «Almazy Anabara» JSC.

Optimization of the composition and properties of heterocomposite materials for coatings obtained by the activation-heliotechnological method

The article presents the results of research on the development of compositions and the study of the properties of heterocomposite materials for coatings used for equipment for the collection, storage and transportation of oil and oil and gas products protected from corrosion and hydro abrasive wear. On the basis of the analysis of the existing devices characteristics for the mechanical activation of mineral particles, the mechanical activator installation “System of running drums” was developed. Using Newton’s interpolation formula and Lagrange’s method, trigonometric and functional factors were determined, regression equations were derived, which were used to determine the optimal type of filler and the quantitative effect of the compositions and properties of composite coatings and the exploited aggressive environment influence on the properties of the material. Analysis of the results of theoretical and practical research on the rational use of natural minerals can be used as a scientific basis for the targeted use of physicochemical phenomena, in particular priority factors such as the formation of positively and negatively charged particles on the surface of the filler-binder phase division.

Wear resistance of adaptive arc-PVD Ti-Al-Mo-Ni-N coatings under impact loading and hydroabrasive wear

The behavior of Ti-Al-Mo-Ni-N coatings obtained by arc-PVD deposition under conditions of impact loading and hydroabrasive wear is studied. Nanostructured coatings samples with a thickness of 4 µm with a modulation period of 30 nm and hardness of 45 GPa were obtained. Under impact loading, the coating performs a protective function up to 105 loading cycles of 250 N without opening the substrate, and during hydroabrasive tests, after 3 hours of exposure to a flow at a speed of 8.5 m/s, there is a spot wear on the coating surface, opening minor segments oft the substrate area. It is shown that the introduction of Ni into the Ti-Al-Mo-N system leads to the appearance of coating failure by brittle mechanism with delamination and opening of the substrate under significant loads in the case of impact and hydroabrasive wear.

Multifunctional sealants based on liquid rubbers with enhanced physical and mechanical properties

Composite Material Research (elastomers) based on liquid isoprene rubber with oxazolidinones -carbanate isocyanate heterochains polar blocks with increased physical and mechanical technical properties are presented in the article.. The developed elastomeric materials have a complex of high physical and mechanical characteristics, are resistant to solutions of mineral acids and alkalis, have shown high resistance to abrasive and hydroabrasive wear, and can also be used to protect technological equipment from the influence of aggressive solutions in the chemical, mining, and hydrometallurgical industries as sealants, protective coatings, structural products, etc.