JP7632015B2 - Receiving drain cleaning device - Google Patents

Description

The present invention relates to a cleaning device for receiving tubing that is installed below a belt conveyor that transports powdered materials such as ore.

A known wet smelting method for nickel oxide ore is the high-temperature pressure acid leach method using sulfuric acid, also known as the HPAL (High Pressure Acid Leach) method. Unlike the conventional dry smelting method for nickel oxide ore, this high-temperature pressure acid leach method does not include dry processing steps such as reduction and drying, and uses a consistent wet process from the raw nickel oxide ore to the production of nickel sulfide, making it an advantageous smelting method in terms of cost and energy consumption. Even if the raw ore used is a low-grade nickel ore with a nickel content of about 1%, it is possible to efficiently increase the nickel content of the finished nickel sulfide to about 50%.

In HPAL plants that process nickel oxide ores using the above-mentioned high-temperature pressure acid leaching method, the nickel raw ore produced from the mine must be transported to the HPAL plant site. For this reason, the HPAL plant generally has one or more belt conveyors installed to transport the nickel oxide ore crushed by a crusher installed in the mine's quarry to equipment such as a hopper or a nearby stockpile.

In addition, in factories other than the HPAL plant, belt conveyors are widely used to transport powdered materials such as ores, soil, and coal. In belt conveyors that handle the above powdered materials, problems such as the belt meandering and damage to the side skirts at both ends of the belt width direction can occur during long-term operation, and as a result, the powdered materials may fall from the belt conveyor and gradually accumulate on the floor surface, etc. If the powdered materials accumulated on the floor surface, etc. are left as they are, the conveying rollers of the belt conveyor may entangle the powdered materials and damage the bearings and other mechanisms, resulting in poor rotation and increased resistance during conveyor travel, and idling at the head pulley, making the transport unstable. In addition, if the accumulated powdered materials come into contact with the belt, they may wear out and develop into major equipment problems such as breakage.

As a countermeasure to this problem, for example, Patent Document 1 discloses a technology in which a scraper acting as a belt cleaner is pressed from below against the belt traveling in the return path near the head pulley of the belt conveyor, and a pressure roller is pressed against the belt from above, scraping off powder particles adhering to the surface of the belt, which are then collected in a collection case provided below the scraper.

However, while the technology of Patent Document 1 mentioned above can prevent powder from accumulating on the floor surface near the head pulley, it cannot prevent powder from accumulating on the floor surface other than near the head pulley, for example, along the conveyor belt's transport path or near the tail pulley. Therefore, there is a risk that powder will fall from the belt surface along the transport path or near the tail pulley and accumulate on the floor below, causing the unstable running and equipment trouble mentioned above.

Patent document 2 also discloses a technology in which a receiving trough for receiving dust that falls from a belt conveyor is installed below the belt conveyor at an angle along the conveyor's transport path, and a cleaning device is provided upstream of the receiving trough, from which water is intermittently poured to clean the receiving trough. The cleaning device in Patent document 2 is designed so that the amount of washing water flowing out is greater in the latter half of the wash than in the first half, and it is described as being able to improve the cleaning power when cleaning the receiving trough.

Japanese Utility Model Application Publication No. 7-40628 JP 2020-37487 A

As described above, when powder or granular material as the transported material adheres to the belt surface of the belt conveyor, the powder or granular material does not fall at the end on the head pulley side, but instead goes around to the return side and is often scraped off by a specific return roller section installed on the path on the return side. This makes it easy for the powder or granular material to accumulate in a specific position in the receiving trough installed below the belt conveyor. However, with the technology of Patent Document 2 above, it was difficult to efficiently remove powder or granular material that had accumulated in such a specific position.

The present invention was made in consideration of the problems with the conventional belt conveyors described above, and aims to provide a receiving trough cleaning device with a simple structure that can efficiently remove powder and granular material that has accumulated inside a receiving trough that is installed below a belt conveyor along the conveying path of the belt conveyor to receive powder and granular material that falls from the belt conveyor.

In order to achieve the above-mentioned object, the receiving trough cleaning device of the present invention is a receiving trough cleaning device that removes deposits of transported materials that have fallen and accumulated in a receiving trough provided along a transport path below a belt conveyor by washing with water, and is composed of a cleaning water supply pipe extending in the width direction of the receiving trough and a plurality of spray nozzles provided on the cleaning water supply pipe along its axial direction, and each of the plurality of spray nozzles has a nozzle directed so as to spray cleaning water diagonally from above onto the deposits on the receiving trough and push them away toward the downstream side of the receiving trough, and each nozzle of the plurality of spray nozzles sprays cleaning water toward the point on the receiving trough where the transported materials that have been scraped off by a spiral return roller provided on the transport path on the return side of the belt conveyor fall .

According to the present invention, powder and granular material accumulated inside a receiving trough installed below a conveyor belt can be effectively removed using a simple structure.

1 is a schematic side view of a belt conveyor having a receiving trough equipped with a receiving trough cleaning device of the present invention provided therebelow. 1 is a perspective view of an embodiment of a gutter cleaning device according to the present invention; 3 is a cross-sectional view of a cleaning water supply pipe of the receiving trough cleaning device of FIG. 2 cut in a cross section perpendicular to its axial direction. 3A is a perspective view showing a specific example of a spray pattern of a spray nozzle of the receiving gutter cleaning device of FIG. 2, and FIG. 3B is a front view of the spray nozzle's spray port.

The following describes an embodiment of the receiving trough cleaning device according to the present invention with reference to the drawings. First, with reference to FIG. 1, we will describe a belt conveyor with a receiving trough equipped with the receiving trough cleaning device of the present invention installed below it. The belt conveyor shown in FIG. 1 is mainly composed of a head pulley 1 and a tail pulley 2 rotatably installed at the front and rear ends, respectively, of a skeletal frame (not shown), and an endless belt B wound around both of these pulleys.

Of the above-mentioned belt conveyor transport paths, the path on which the transported object is transported from the tail pulley 2 to the head pulley 1 is called the carrier side, and the path on which the belt B returns from the head pulley 1 to the tail pulley 2 is called the return side. A number of carrier rollers 3 are provided at regular intervals to support the belt B on the former carrier side, and a number of return rollers 4 are provided at regular intervals to support the belt B on the latter return side. Some of the return rollers 4 are spiral return rollers 4a that have the function of scraping off the adhesion of the transported object that causes the belt B to meander or become biased while rotating. The most downstream return roller on the return side is a reverse adjustment return roller 4b that has the ability to correct the meandering of the return belt.

A snap pulley 5 is provided immediately downstream of the head pulley 1, and its mounting position can be adjusted to increase the winding angle of the head pulley 1. This allows more of the belt B to be wound around the outer periphery of the head pulley 1, so the rotational drive force of the head pulley can be transmitted more reliably to the belt B, allowing it to run stably, and preventing problems with the belt B spinning freely or slipping on the outer periphery of the head pulley 1.

On the return side of belt B, there is further provided a weight pulley 6 and a pair of bend pulleys 7 located immediately upstream and downstream of the weight pulley 6. Tension is applied to belt B by the weight pulley 6 and the aforementioned snap pulley 5. Furthermore, on the return side of belt B, there is provided a forced centering roller 8 that presses belt B downward to center it.

In a belt conveyor having the above-mentioned mechanism, the following are some of the reasons why the powdered material being conveyed falls off the conveyor surface, for example, when the powdered material is ore. That is, the ore, which is quantitatively extracted from the bottom of the hopper H by a screw feeder or the like, is placed on the end of the belt conveyor on the tail pulley 2 side, and is transported along a carrier-side path that is generally horizontal or diagonally upward toward a specified destination, and then falls by gravity from the end on the head pulley 1 side located at the destination. The ore transported in this way is adjusted in particle size by pre-processing such as crushing and classification as necessary before transportation, so the size of the ore when transported is often about 150 mm or less, and it is easy for it to fall from both ends of the width of the belt B due to vibrations, etc., on the way from the tail pulley 2 to the head pulley 1.

In addition, some of the ore transported by the belt conveyor may not fall off at the end of the head pulley 1 side, but may remain attached to the belt surface and wrap around to the return side. To prevent this, a primary scraper 10 and a secondary scraper 11 are attached to the head pulley 1, which scrape off the ore that has adhered to the belt surface. However, if the moisture content of the ore is high, even these scrapers 10 and 11 may not be able to scrape off enough of the ore from the belt surface, and for example, ore that is about 0.5 mm under may wrap around to the return side of the conveyor while remaining attached to the belt surface. Most of the ore that wraps around to the return side is scraped off by the spiral return roller 4a and falls. The above phenomenon in which ore falls from the belt conveyor is sometimes called ore falling.

In order to receive ore falling mainly due to the above-mentioned causes, a receiving trough 20 is provided below the belt conveyor along the conveying path of belt B. The ore falling received in this receiving trough 20 is more likely to be ore scraped off and falling by the spiral return roller 4a provided on the conveying path on the return side of belt B than ore with a relatively small particle size of about 100 mm or less that falls midway along the conveying path on the carrier side of belt B. As a result, deposits due to ore falling tend to form locally inside the receiving trough 20, which causes damage to the return roller 4 and belt B.

In other words, when the ore received in the receiving culvert 20 accumulates and reaches the height of the spiral return roller 4a, the ore gets caught in the bearing, preventing the spiral return roller 4a from rotating, which creates resistance to the movement of belt B and makes the tension of belt B unstable. As a result, stress is concentrated in the spliced parts and already damaged parts of belt B, causing belt B to break.

In order to remove the deposits from the transported objects that have fallen and accumulated in the receiving trough 20 provided below the conveyor belt, the receiving trough cleaning device 30 according to an embodiment of the present invention is provided in the receiving trough 20. Specifically, as shown in FIG. 2, the receiving trough cleaning device 30 according to an embodiment of the present invention is composed of a cleaning water supply pipe 31 extending in the width direction of the receiving trough 20 and a plurality of spray nozzles 32 preferably provided at equal intervals along the axial direction of the cleaning water supply pipe 31. The cleaning water supply pipe 31 is connected to a cleaning water supply line (not shown), and cleaning water having a predetermined water pressure is introduced into the cleaning water supply pipe 31. The cleaning water supply line and the end of the cleaning water supply pipe 31 are preferably connected via a coupler 33 having a cam lock structure.

Each of the spray nozzles 32 has a nozzle directed so as to spray the cleaning water from an oblique upward direction against the deposits on the receiving tub 20 and to push them toward the downstream side of the receiving tub 20 corresponding to the downstream side of the return-side path of the belt conveyor. Specifically, as shown in FIG. 3, when viewed from the axial direction of the cleaning water supply pipe 31, the nozzle of each spray nozzle 32 is preferably directed within a range of about 35° to 55°, more preferably 45°, between the direction of the cleaning water sprayed toward the drop point of the ore from the spiral return roller 4a on the bottom surface 20a of the receiving tub 20 and the perpendicular line to the bottom surface 20a of the receiving tub 20. In addition, the shortest distance between the center of the nozzle and the bottom surface 20a of the receiving tub 20 is preferably 110 mm to 130 mm. Furthermore, the total flow rate of the cleaning water sprayed from the spray nozzles 32 is preferably 15 m ³ to 30 m ³ per hour. This allows the deposits accumulated inside the receiving gutter 20 to be effectively washed away.

As mentioned above, ore falls are likely to accumulate at the point where the ore scraped off by the spiral return rollers 4a installed on the return side of the conveyor belt falls, so the receiving trough cleaning device 30 is preferably positioned to spray cleaning water toward the point where the ore scraped off by the spiral return rollers 4a falls on the receiving trough 20. In this case, it is desirable to attach the receiving trough cleaning device 30 to all spiral return rollers 4a installed on the conveyor belt at a position upstream of the point where the ore falls from them falls on the receiving trough 20, in relation to the return side of the conveyor belt.

However, if it is difficult to provide the device near the drop points from all of the spiral return rollers 4a as described above due to space limitations, cost, etc., it is preferable to provide the receiving trough cleaning device 30 at least near the drop points from the spiral return roller 4a attached at the position closest to the head pulley 1. The reason for this is that the receiving trough 20 is generally provided at an incline so that the lower end of the head pulley 1 is higher than the lower end of the tail pulley 2, so by providing the receiving trough cleaning device 30 near the drop point from the spiral return roller 4a attached at the position closest to the head pulley 1 as described above, it is expected that the deposits that have fallen from the spiral return roller 4a attached downstream of that and accumulated in the receiving trough 20 can also be cleaned. Alternatively, the receiving trough cleaning device 30 may be provided near the drop points of each of the spiral return rollers 4a provided along the return side transport path, not for all of them, but for every two or so.

The above-mentioned receiving trough cleaning device 30 may spray cleaning water continuously or intermittently. When spraying intermittently from multiple receiving trough cleaning devices 30, the spray timing may be staggered. In addition, the receiving trough cleaning device 30 installed near the landing point of the spiral return roller 4a attached at the position closest to the head pulley 1 may spray continuously, and the other receiving trough cleaning devices 30 may spray intermittently.

The ore slurry made with the washing water sprayed from the receiving culvert cleaning device 30 flows through the receiving culvert 20 and is discharged from its downstream end. The ore slurry discharged from the end of the receiving culvert 20 is temporarily stored in a pit, and then extracted by a sump pump in the pit and collected in a reservoir or the like. After that, solid-liquid separation is performed as necessary, and the ore is used as raw material in the production plant.

As described above, by using the receiving trough cleaning device of the embodiment of the present invention, even if the ore being transported by the belt conveyor falls from both ends in the width direction due to vibration or impact, or if the ore adhered to the belt surface turns around to the return side and is scraped off by a specific roller and falls, causing local accumulation inside the receiving trough, cleaning water can be sprayed intensively on that area to remove the ore, preventing problems such as belt slippage and equipment trouble caused by the accumulation.

A belt conveyor having a structure in which belt B is stretched over head pulley 1 and tail pulley 2 as shown in Figure 1 was used to transport nickel oxide ore at a maximum transport capacity of 540 t/hr by running belt B at a speed of 95 m/min. In this belt conveyor, the distance between the central axis of head pulley 1 and the central axis of tail pulley 2 was approximately 163 m, and belt B had a width of 1050 mm. Below this belt conveyor, a receiving trough 20 was installed along the transport path of belt B at an inclination angle of 10.9° so that the head pulley 1 side was higher than the tail pulley 2 side.

As shown in FIG. 2, three receiving culvert cleaning devices 30 were attached to each of the three spiral return rollers 4a in the receiving culvert 20 at positions upstream of the drop point of the ore on the receiving culvert 20 in the return side transport path, so as to extend in the width direction of the receiving culvert 20. At this time, the distances L ₁ , L ₂ , and L ₃ starting from the central axis of the tail pulley 2 were about 55 m, about 59 m, and about 46 m, respectively. Each of the three receiving culvert cleaning devices 30 was composed of a wash water supply pipe 31 made of carbon steel pipe SGP and 15 spray nozzles 32 arranged at equal intervals of 70 mm in the axial direction, and was connected to a wash water supply line having a valve and a flexible pipe via a cam lock type coupler 33 provided at the end of the wash water supply pipe 31. In this way, industrial water was introduced from the wash water supply line to each receiving culvert cleaning device 30.

The spray nozzle 32 used was a spray nozzle (model number: HB3/8U-SS, material: SUS303) manufactured by Spraying Systems Far East Company, capable of spraying cleaning water in a fan-shaped pattern with a central angle of 40°. By adjusting the valve opening of the above-mentioned cleaning water supply line, the total spray flow rate of cleaning water from the group of spray nozzles 32 provided on one cleaning water supply pipe 31 was set within the range of 15 ^m3 to 30 ^m3 per hour.

When viewed from the axial direction of the cleaning water supply pipe 31, each spray nozzle 32 of each receiving culvert cleaning device 30 is oriented so that the angle θ between the direction of the cleaning water sprayed toward the point on the bottom surface 20a of the receiving culvert 20 where the ore falls from the spiral return roller 4a and the perpendicular to the bottom surface 20a of the receiving culvert 20 is 45°, and the position is adjusted so that the shortest distance between the center of the nozzle and the bottom surface 20a of the receiving culvert 20 is 120 mm. This makes it possible to spray cleaning water from diagonally above against the deposits accumulated in the receiving culvert 20, and to push them toward the downstream side of the receiving culvert 20 corresponding to the downstream side of the return side transport path of the belt conveyor.

In this way, cleaning water was sprayed into the ore receiving trough 20 of the conveyor belt to remove the deposits. The amount of cleaning water sprayed was adjusted by adjusting the valve opening of the cleaning water supply line as appropriate depending on the remaining deposits of the transported materials accumulated in the receiving trough 20. For comparison, a belt conveyor equipped with the above-mentioned receiving trough 20 was operated in the same manner, except that the receiving trough cleaning device 30 was not attached to the receiving trough 20.

The number of belt damages that occurred per month for belt B in each of the embodiment in which the above-mentioned receiving culvert cleaning device 30 was installed and operated, and the comparative example in which the receiving culvert cleaning device 30 was not installed, is shown in Table 1 below. The number of belt damages is defined as the number of times per month that belt B broke or was partially damaged due to ore that had accumulated on the receiving culvert 20. The operating period for the evaluation was 12 months, and the evaluation was based on the average number of belt damages.

As can be seen from Table 1 above, the number of belt damages was an average of 0.08 times/month in the Example and 0.58 times/month in the Comparative Example, which shows that the provision of a receiving culvert cleaning device can effectively remove deposits caused by falling ore inside the receiving culvert. A one-tailed T-test was performed using the average number of belt damages for the Example and Comparative Example, and a significant difference was found in the rejection region of 2.5%.

REFERENCE SIGNS LIST 1 Head pulley 2 Tail pulley 3 Carrier roller 4 Return roller 4a Spiral return roller 4b Reverse type adjustment return roller 5 Snap pulley 6 Weight pulley 7 Bend pulley 8 Forced centering roller 10 Primary scraper 11 Secondary scraper 20 Receiving trough 30 Receiving trough cleaning device 31 Cleaning water supply pipe 32 Spray nozzle 33 Coupler B Belt H Hopper

Claims (3)

A receiving trough cleaning device that removes deposits of transported materials that have fallen and accumulated in a receiving trough provided along a transport path below a belt conveyor by washing with water, the receiving trough cleaning device comprising a cleaning water supply pipe extending in the width direction of the receiving trough and a plurality of spray nozzles provided on the cleaning water supply pipe along its axial direction, each of the plurality of spray nozzles having a nozzle directed so as to spray cleaning water diagonally from above toward the deposits on the receiving trough and to sweep them away toward the downstream side of the receiving trough, and each nozzle of the plurality of spray nozzles sprays cleaning water toward the point on the receiving trough where the transported materials that have been scraped off by a spiral return roller provided on the transport path on the return side of the belt conveyor fall . The receiving trough cleaning device as described in claim 1 , characterized in that the receiving trough cleaning device is provided near the point where the transported objects scraped off by the spiral return roller attached at least in a position closest to the head pulley fall onto the receiving trough. The receiving trough cleaning device described in claim 1, characterized in that the multiple spray nozzles are arranged at equal intervals along the axial direction of the cleaning water supply pipe at a pitch of 30 mm or more and 100 mm or less, and each of the spray nozzles is oriented so that, when viewed from the axial direction of the cleaning water supply pipe, the angle between the spray direction of the cleaning water sprayed toward the drop point and the perpendicular line to the bottom surface of the receiving trough is 35° or more and 55° or less, the shortest distance between the center of the spray nozzle and the bottom surface of the receiving trough is 110 mm or more and 130 mm or less, and the total spray flow rate of the cleaning water is 15 m3 or more and 30 m3 or less per hour.

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