Piping structure

Abstract

To provide a piping structure that can reduce piping perforation trouble due to contact with a transportation object inside the piping.SOLUTION: A piping structure 1 for transporting an abrasive slurry with gravity fall includes: a vertical piping part 10 disposed in a vertical direction; an inclined piping part 20 branching obliquely upward at an angle θ of 30° or more and 60° or less relative to a perpendicular V of the vertical piping part 10; and a liner 30 capable of being inserted into a pipe inner surface from a side of an upper end 11 of the vertical piping part 10 and protecting a branching part between the vertical piping part 10 and the inclined piping part 20 with a wear-resistant material.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a piping structure capable of reducing the occurrence of pipe perforation problems caused by contact with transported goods inside the piping. [Background technology]

[0002] One method for recovering nickel from low-grade nickel oxide ores is the high-pressure acid leaching (HPAL) method using sulfuric acid. This method does not include dry processing steps such as drying and roasting, and instead consists of a consistent wet process, so it is advantageous in terms of energy and cost, and has the advantage of being able to obtain nickel-cobalt mixed sulfide with nickel content increased to about 50% by weight.

[0003] In the hydrometallurgical smelting of nickel oxide ores, the raw ore often contains chromite. Such chromite ores contain almost no nickel, and it is known that when the ore slurry containing chromite is transported using equipment such as piping and pumps for acid leaching, the equipment is significantly worn out, which has a significant impact on the maintenance and operation efficiency of the equipment.

[0004] For this reason, chromite is collected as a by-product in the hydrometallurgical smelting process of nickel oxide ore. Chromite has a high true density among nickel oxide ores, and its particle size is large, so it tends to settle in liquids. Chromite is also known as a relatively hard particle in nickel ore, and is used industrially as an abrasive.

[0005] In the wet refining of nickel oxide ore, chromite causes wear to equipment and piping. Specifically, when chromite is pumped as a slurry, equipment such as pumps, piping, and valves wear at the points where they come into contact with the slurry. Among these, wear is particularly noticeable at points where the fluid in the piping falls due to gravity and where the piping is bent. In such points, when using conventional general piping methods, there are frequent cases where the equipment operating rate drops due to pipe holes.

[0006] To address such issues, for example, Patent Document 1 discloses a method for preventing wear on bent pipe sections during slurry transport, in which the curvature is gradually changed to create a shape that can minimize changes in the slurry density in the bent pipe section, thereby preventing wear.

[0007] However, it is difficult to create a curved pipe section whose curvature changes gradually as in Patent Document 1 because of the number of steps required.

[0008] Furthermore, Patent Document 2 discloses a slurry pipe characterized in that a replaceable liner made of an abrasion-resistant material is provided on the inner surface of the pipe, and fixing bolts of an appropriate length are provided on the outer surface of the pipe for fixing the liner to the inner surface of the pipe.

[0009] However, when replacing the liner, it is necessary to remove the entire pipe, which causes a problem that the liner replacement work requires a lot of man-hours. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] Japanese Utility Model Application Publication No. 57-130100 [Patent Document 2] Japanese Utility Model Application Publication No. 50-17812 Summary of the Invention [Problem to be solved by the invention]

[0011] The present invention has been proposed in consideration of the above-mentioned circumstances, and has an object to provide a piping structure that can reduce the trouble of piping holes being formed due to contact with the transported goods inside the piping. [Means for solving the problem]

[0012] One aspect of the present invention is a piping structure for transporting abrasive slurry by gravity, characterized in that it comprises a vertical piping section arranged vertically, an inclined piping section branching diagonally upward at an angle of 30° or more and 60° or less with respect to the perpendicular to the vertical piping section, and a liner that can be inserted into the inner surface of the pipe from the upper end side of the vertical piping section and that protects the branching point between the vertical piping section and the inclined piping section with an abrasion-resistant material.

[0013] In this case, in one aspect of the present invention, the liner may be provided with a deflection guide that protrudes toward the inclined piping section and on which part of the abrasive slurry accumulates.

[0014] In one aspect of the invention, the abrasive slurry may include chromite particles.

[0015] In one embodiment of the present invention, the liner may have a horizontal cross section that is sector-shaped, with a central angle of 130° or more and 180° or less.

[0016] In one aspect of the present invention, the upper portion of the liner may be provided with a lid and a handle that cover the upper end of the vertical piping portion.

[0017] In addition, in one aspect of the present invention, the direction change guide is provided at a point where the abrasive slurry sent from the inclined piping section collides with the wall surface of the vertical piping section when the liner is installed in the vertical piping section, and may have an angle of 30 degrees or more and 60 degrees or less with respect to the perpendicular line of the vertical piping section, and may have a semicircular shape welded to the inner circumference of the liner.

[0018] In one aspect of the present invention, a portion of the abrasive slurry may be deposited on the direction change guide, thereby providing a coating function for the portion that collides with the wall surface of the vertical piping section.

[0019] In addition, in one aspect of the present invention, the liner may be attached to the vertical piping section with its center at the point where the center line of the inclined piping section and the vertical piping section intersect. Effect of the Invention

[0020] According to the present invention, a piping structure can be provided that reduces the trouble of holes in the piping caused by contact with transported goods inside the piping. [Brief description of the drawings]

[0021] [Figure 1] FIG. 1 is a process diagram showing an example of a process for separating chromite from nickel oxide ore. [Diagram 2] FIG. 1A is a schematic diagram showing a conventional piping structure, and FIG. 1B is a perspective view showing the inside of FIG. [Diagram 3] 1 is a schematic diagram showing a piping structure according to an embodiment of the present invention; [Figure 4] 1 is a schematic diagram showing a structure of a liner in a piping structure according to one embodiment of the present invention. [Diagram 5] 1 is a horizontal cross-sectional view showing a state in which a liner is inserted into a piping structure according to one embodiment of the present invention. [Figure 6] 1 is a perspective view showing the inside of a piping structure according to an embodiment of the present invention; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] Preferred embodiments of the present invention will be described in detail below with reference to the drawings in the following order. Note that the embodiments described below do not unduly limit the contents of the present invention described in the claims, and all of the configurations described in the embodiments are not necessarily essential as the means for solving the problems of the present invention. 1. Chromite classification process 2. Piping structure

[0023] <1. Chromite classification process> The piping structure according to one embodiment of the present invention can be applied, for example, to a process for transporting a slurry in a classification process of chromite containing water, which is recovered as a by-product in a nickel oxide ore smelting process. Of course, the present invention is not necessarily limited to the transportation of chromite, and can be applied to other situations in which an abrasive slurry is transported by gravity through a piping.

[0024] First, a process for obtaining chromite-containing ore in a hydrometallurgical process for nickel oxide ore will be described.

[0025] Nickel oxide ores, which are raw materials to be processed in the hydrometallurgical process of nickel oxide ores, are mainly so-called laterite ores such as limonite ore and saprolite ore. The nickel content of laterite ores is usually 0.8 to 2.5% by weight, and nickel is contained as hydroxide or hydrous magnesium silicate (magnesium silicate) mineral. The iron content is 10 to 50% by weight, and is mainly in the form of trivalent hydroxide (goethite), but some divalent iron is contained in hydrous magnesium silicate mineral, etc.

[0026] Furthermore, laterite ore contains chromium, and most of the chromium is contained as chromite minerals containing iron or magnesium, for example, at about 1 to 5% by weight. Magnesia is contained in hydrous magnesium siliceous minerals as well as in unweathered, hard magnesium siliceous minerals that contain almost no nickel. Silica is contained in silica minerals such as quartz and cristobalite (amorphous silica) and hydrous magnesium siliceous minerals. Thus, the chromite minerals, magnesium siliceous minerals, and silica minerals contained in laterite ore are so-called gangue components that contain almost no nickel.

[0027] In the hydrometallurgical smelting process of nickel oxide ore, the raw material nickel oxide ore, which is mainly laterite ore, is adjusted in particle size and then mixed with water to prepare an ore slurry, which contains chromite as described above. It is known that when such an ore slurry containing chromite is transported using equipment such as piping and pumps for acid leaching treatment, the equipment is significantly worn, which has a significant impact on the maintenance and operating efficiency of the equipment. For this reason, the chromite content is separated and removed from the ore slurry to be subjected to acid leaching treatment prior to the acid leaching treatment.

[0028] Figure 1 shows a process diagram of an example of a process for separating chromite from nickel oxide ore. In a hydrometallurgical process based on high pressure sulfuric acid leaching (HPAL) for recovering nickel from low-grade nickel oxide ore, the raw nickel ore is transported and supplied from the mine, but the large-grained ore in the ore needs to be removed because it has a low leaching rate with acid.

[0029] In the pre-treatment step S1, large-sized ores are removed by a washing and screening device. As the washing and screening device, a drum washer consisting of a drum and a trommel, and a vibrating screening device are used. The drum of the drum washer has the function of crushing and repulping (loosening) the nickel oxide ore to make an ore slurry, and the ore is sent to the trommel side by a recovery blade provided on the connecting side of the drum with the trommel. The trommel has the function of screening the ore contained in the ore slurry.

[0030] In the pre-treatment process S1, the ore slurry is screened by the trommel of the drum washer to remove ore with a particle size of 25 mm or more, and then the ore with a particle size of approximately 2 mm or less is sent to the next process via a vibrating sieve device.

[0031] In the centrifugal separation step S2, the ore slurry of 2 mm or less obtained in the pretreatment step S1 is classified into a coarse-particle slurry and a fine-particle slurry at a predetermined classification particle size (classification point) using a hydrocyclone, and the slurry is classified into a coarse-particle slurry and a fine-particle slurry. As a result, a mixture containing chromite is obtained in the coarse-particle slurry separated as the underflow of the hydrocyclone, and a mixture containing goethite containing iron is obtained in the fine-particle slurry separated as the overflow. This allows the chromite to be separated from the ore slurry in the first stage.

[0032] In general, the specific gravity of chromite is greater than that of iron hydroxide such as goethite. Therefore, by using a hydrocyclone as a classification device, the ore slurry can be accurately separated based on particle size into a mixture containing chromite as an underflow and a mixture containing goethite as an overflow. Furthermore, hydrocyclones are suitable for treating large amounts of ore slurry, and are suitable for treating cases in which a large amount of ore is distributed to the overflow. The hydrocyclone may have only one stage, or may have multiple stages of two or more stages.

[0033] In the gravity separation step S3, the mixture containing chromite separated as an underflow in the centrifugation step S2 is subjected to gravity separation treatment using a specified gravity separator, and goethite contained in the mixture containing chromite is separated to obtain a mixture in which chromite is concentrated. The mixture containing chromite separated as an underflow in the centrifugation step S2 mainly contains chromite, but also contains some goethite. By subjecting such a mixture containing chromite to gravity separation treatment using the gravity separator, it is possible to further effectively separate goethite from chromite, and to further concentrate chromite.

[0034] As an example of the gravity separation device in the gravity separation step S3, at least one stage of a spiral concentrator is used. In addition, in this gravity separation process, it is preferable to use at least one stage of a spiral concentrator and one or more stages selected from a shaking table, a density separator, and a spiral concentrator. Among them, it is particularly preferable to combine one stage of a spiral concentrator with a process using a density separator suitable for large-volume processing. The piping structure according to one embodiment of the present invention is applied in the process in which the slurry separated by particle size using the spiral concentrator is sent to a receiving tank.

[0035] In the concentration step S4, the slurry concentration of the pre-concentration slurry processed in the preceding gravity separation step S3 is adjusted so as to be a preferable slurry concentration as a supply condition for a magnetic separator employed in the following magnetic separation step S5. There is no particular limitation on the type of concentration device used in this concentration step S4, but a gravity settling device such as a thickener that can concentrate the slurry at a relatively low cost is preferred.

[0036] In the magnetic separation step S5, a magnetic separator is used to remove magnetized matter from the concentrated slurry that has been concentrated in the previous concentration step S4. The coarse-particle slurry that has been separated and classified into the coarse-particle side in the centrifugation step S2 is mainly composed of chromite, but may contain magnetite and also goethite. In the magnetic separation step S5, the concentrated slurry that contains other mineral components in addition to chromite is subjected to magnetic separation treatment, so that magnetite as a magnetized matter can be separated from chromite as a non-magnetized matter, and the chromite can be further concentrated.

[0037] The mixture containing magnetite as the magnetized matter separated in the magnetic separation step S5 can be mixed with the overflow of the hydrocyclone described above to produce a chromite-free ore slurry to be treated in the acid leaching process of the hydrometallurgical process. In addition, if a trace amount of goethite is contained in the concentrated slurry to be treated in the magnetic separation process, it can be included in the mixture containing magnetite by the magnetic separation process, and can be used as the ore slurry to be supplied to the acid leaching process together with magnetite.

[0038] In the dehydration step S6, the chromite obtained in the previous steps is dried until it has a moisture content suitable for shipping and transportation as a product. Ore containing chromite as the main component has a particle size in the range of about 100 μm to 1 mm, and the weight moisture content immediately after the separation step is about 12% to 15%. In general, it is necessary to reduce the moisture content of chromite-containing ore to about 7% to 8%.

[0039] The dehydration treatment of the ore in the dehydration step S6 can be performed by sun drying, heating / roasting, filter press, centrifugal separation, etc. However, since it does not require the use of energy such as electricity, a method in which the chromite ore is piled up on a dehydration bed in a pile shape (mountain shape) and dehydrated and dried by its own weight is preferred.

[0040] <2. Piping structure> The piping structure according to one embodiment of the present invention is applied, for example, to the path of the slurry separated by particle size in the spiral concentrator in the gravity separation step S3 described above until it is sent to the receiving tank. The spiral concentrator is a separation device equipped with a slurry flow path that is a spiral inclined slide. Mineral particles with different specific gravities mixed in the slurry are separated by gravity difference while flowing through the slurry flow path that is a spiral inclined slide of the spiral concentrator, and the coarse and heavy chromite ore passes through the innermost flow basin zone, the light and coarse gangue consisting of silica minerals and magnesia ore in addition to chromite ore passes through the intermediate flow basin zone, and the goethite, gangue, and much water are recovered from the outermost tailings flow basin zone. The slurry that slides down the slope of the spiral concentrator in this way falls by gravity through the piping to the next receiving layer. The particle size of the chromite slurry, which is an abrasive slurry, at this stage has an average particle size of 150 μm.

[0041] Fig. 2(A) is a schematic diagram showing a conventional piping structure, and Fig. 2(B) is a perspective view showing the inside of Fig. 2(A). In the conventional piping structure 100, as shown in Fig. 2(A), the slurry classified by the spiral concentrator passes through the inclined piping section 101 and is discharged from the vertical piping section 102 to a receiving tank below. In the case of the slurry flowing through the piping, in the case of chromite particles 103, the difference in specific gravity between the chromite particles 103 and the liquid (water) is very large, so the chromite particles 103 settle to the bottom of the piping, and the chromite particles 103 collide intensively with the piping material at the bend 104 of the piping, causing problems such as holes in the piping.

[0042] 3 is a schematic diagram showing a piping structure according to one embodiment of the present invention that solves the above problems. One aspect of the present invention is a piping structure 1 that transports abrasive slurry by gravity, and is characterized by including a vertical piping section 10 arranged in a vertical direction, an inclined piping section 20 that branches obliquely upward at an angle θ of 30° or more and 60° or less with respect to a perpendicular line V of the vertical piping section 10, and a liner 30 that can be inserted into the inner surface of the pipe from the upper end 11 side of the vertical piping section 10 and protects the branching point between the vertical piping section 10 and the inclined piping section 20 with an abrasion-resistant material.

[0043] In the present invention, a branched structure is provided in which a removable liner 30 can be inserted into the bent portion of the pipe, and the slurry particles flowing inside the pipe collide with the liner 30 and do not collide directly with the piping material. This results in a piping structure that reduces the trouble of holes in the pipe caused by contact with the transported material inside the pipe.

[0044] 3, the inclined piping section 20 is connected obliquely upward at an angle θ of 30° or more and 60° or less with respect to the perpendicular line V of the vertical piping section 10. If the angle is less than 30°, there is a problem that the slurry may clog the piping, and if the angle exceeds 60°, the design freedom of the equipment layout between the upstream and downstream processes is reduced.

[0045] 4 is a schematic diagram showing the structure of a liner in a piping structure according to an embodiment of the present invention. In one aspect of the present invention, the liner 30 is provided with a main body 31 that protects the inner surface of the piping from the abrasive slurry, and a direction-changing guide 32 that protrudes toward the inclined piping section 20 and on which a part of the abrasive slurry accumulates. By providing such a direction-changing guide 32, as described below, a part of the abrasive slurry can be intentionally accumulated on the direction-changing guide 32, and the accumulated slurry particles can exhibit a self-coating function.

[0046] The main body 31 of the liner 30 to be inserted into the pipe is preferably made of a metal having wear resistance. Since chromite is a particle with high hardness, it is desirable to use a metal having a certain strength and wear resistance as the material of the liner. One example of the material is HARDOX (registered trademark), which is a high-strength material.

[0047] 5 is a horizontal cross-sectional view showing a state in which a liner is inserted into a piping structure according to one embodiment of the present invention. In one embodiment of the present invention, the main body 31 of the liner 30 has a horizontal cross-section in the shape of a sector, and the central angle φ is preferably 130° or more and 180° or less. As described above, since abrasive slurry such as chromite flows from the inclined piping section 20 side and collides with the inner surface of the vertical piping section 10, the main body 31 of the liner 30 is preferably in the above-mentioned numerical range so as to widely cover the inner surface side of the vertical piping section 10 where the slurry particles collide while not covering the inclined piping section 20 side.

[0048] In one embodiment of the present invention, as shown in Fig. 4, the upper part of the liner 30 is preferably provided with a lid 33 that covers the upper end 11 of the vertical piping section 10 and a handle 34. The provision of the lid 33 makes it possible to prevent slurry particles and the like from scattering from the upper end 11 of the vertical piping section 10, and the provision of the handle 34 makes it possible to easily attach and detach the liner 30 to and from the vertical piping section 10.

[0049] In one embodiment of the present invention, the direction change guide 32 is provided at a position where the abrasive slurry sent from the inclined piping section 20 collides with the wall surface of the vertical piping section 10 when the liner 30 is installed in the vertical piping section 10, and preferably has an angle τ of 30° or more and 60° or less with respect to the perpendicular line V of the vertical piping section 10 and has a semicircular shape welded to the inner circumference of the liner 30. In addition, the length of the direction change guide 32 in the protruding direction is preferably 30% to 40% of the radius of the vertical piping section 10.

[0050] Fig. 6 is a perspective view showing the inside of a piping structure according to an embodiment of the present invention. In one aspect of the present invention, a turning guide 32 is provided on the liner 30, so that a part of the abrasive slurry 40 is deposited on the turning guide 32 to form a self-coating portion 45, as shown in Fig. 6. Then, the subsequent abrasive slurry 40 collides with the self-coating portion 45 formed by the deposited slurry, and the self-coating portion 45 can also cushion the impact. The self-coating portion 45 and the main body portion 31 of the liner 30 can doubly cushion the impact of the abrasive slurry 40, thereby improving the function of protecting the piping.

[0051] If the installation angle τ of the direction change guide 32 is less than 30°, the collision area of ​​the chromite slurry becomes narrow, and the impact mitigation effect in the self-coating section 45 decreases. If the angle exceeds 60°, the abrasive slurry 40 becomes less likely to remain or become clogged in the groove of the direction change guide 32, and the impact mitigation effect in the self-coating section 45 decreases. Therefore, it is preferable that the installation angle τ of the direction change guide 32 be 30° or more and 60° or less with respect to the perpendicular line V of the vertical piping section 10.

[0052] In one embodiment of the present invention, the liner 30 is preferably attached to the vertical piping section 10 with its center at point P (see FIG. 3) where the center line C of the inclined piping section 20 intersects with the vertical piping section 10. The vicinity of this point is where the abrasive slurry 40 collides with the inner wall surface of the vertical piping section 10, so it is preferable to install the liner 30 at this point.

[0053] As described above, according to the present invention, it is possible to reduce the trouble of holes in the pipes caused by contact with the transported goods inside the pipes. EXAMPLES

[0054] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples in any way.

[0055] The effect of applying a piping structure according to one embodiment of the present invention to a chromite recovery process in a hydrometallurgical process for nickel oxide ore was verified.

[0056] (Comparative Example) In a comparative example (conventional example), a slurry containing chromite particles classified by a spiral concentrator was transported by the conventional piping structure shown in Figure 2. The liquid component (water) of the slurry had a density of 1.0 and a flow rate of 10.1 m 3 / hr, and for particulate matter (chromite), the density is 4.28 and the flow rate is 4.5 m 3 This process was run 24 hours a day, but within a month, holes would appear in the piping where the chromite particles collided, requiring the operation to be stopped for about five hours each time the piping was repaired.

[0057] (Example) In the examples, operation was performed by applying a piping structure according to one embodiment of the present invention as shown in Fig. 3. In the examples, since the liner can be easily attached and detached, the condition of the liner was checked about once a week and maintained in an appropriate condition, which made it possible to completely prevent the trouble of holes in the piping.

[0058] From the above results, it was confirmed that the application of the piping structure according to the present invention can reduce the trouble of piping holes being formed due to contact with the transported goods inside the piping.

[0059] Although one embodiment of the present invention and each example have been described in detail above, it will be readily apparent to those skilled in the art that many modifications are possible without substantially departing from the novel features and effects of the present invention. Therefore, all such modifications are intended to be included within the scope of the present invention.

[0060] For example, a term described at least once in the specification or drawings together with a different term having a broader or similar meaning may be replaced with the different term anywhere in the specification or drawings. In addition, the configuration of the piping structure is not limited to the one described in the embodiment and each example of the present invention, and various modifications are possible. [Explanation of symbols]

[0061] 1 Pipe structure, 10 Vertical pipe section, 11 Upper end (of vertical pipe section), 20 Slanted pipe section, 30 Liner, 31 Main body, 32 Turning guide, 33 Lid, 34 Handle, 40 Abrasive slurry, 45 Self-coating section, 100 Conventional pipe structure, 101 Slanted pipe section, 102 Vertical pipe section, 103 Chromite particles, C Center line of the Slanted pipe section, V Vertical line of the vertical pipe section, P Intersection point of the center line of the Slanted pipe section and the vertical pipe section, θ Angle between the Slanted pipe section and the vertical pipe section, φ Central angle of the horizontal cross section of the liner, τ Installation angle of the turning guide

Claims

1. A piping structure for transporting an abrasive slurry by gravity, comprising: A vertical piping section disposed vertically; an inclined piping section that branches diagonally upward at an angle of 30° or more and 60° or less with respect to a perpendicular line of the vertical piping section; A liner that can be inserted into the inner surface of the vertical piping section from the upper end side of the vertical piping section and protects the branching point between the vertical piping section and the inclined piping section with an abrasion resistant material. A piping structure comprising:

2. 2. The piping structure according to claim 1, wherein the liner is provided with a deflection guide that protrudes toward the inclined piping section and on which a portion of the abrasive slurry accumulates.

3. 3. The piping arrangement of claim 2, wherein the abrasive slurry includes chromite particles.

4. 4. The piping structure according to claim 3, wherein the liner has a horizontal cross section that is sector-shaped and has a central angle of 130° or more and 180° or less.

5. The piping structure according to claim 4 , wherein an upper portion of the liner is provided with a lid and a handle for covering an upper end of the vertical piping portion.

6. The piping structure described in claim 5, characterized in that the direction change guide is provided at a point where the abrasive slurry sent from the inclined piping section collides with the wall surface of the vertical piping section when the liner is installed in the vertical piping section, has an angle of 30° or more and 60° or less with respect to the perpendicular line of the vertical piping section, and has a semicircular shape welded to the inner circumference of the liner.

7. 7. The piping structure according to claim 6, wherein a portion of the abrasive slurry is deposited on the direction change guide, thereby providing a coating function for a portion that collides with a wall surface of the vertical piping section.

8. The piping structure according to claim 7, wherein the liner is attached to the vertical piping section with the center being a point where a center line of the inclined piping section and the vertical piping section intersect.

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