AU2015241974A1

AU2015241974A1 - Method of processing water-containing bulk material and apparatus for adding flocculant to water-containing bulk material

Info

Publication number: AU2015241974A1
Application number: AU2015241974A
Authority: AU
Inventors: Yasutoshi Inoue; Yuki KINUGASA
Original assignee: JFE Steel Corp
Current assignee: JFE Steel Corp
Priority date: 2014-04-01
Filing date: 2015-04-01
Publication date: 2016-09-29
Anticipated expiration: 2035-04-01
Also published as: JP6505668B2; JPWO2015151524A1; WO2015151524A1; AU2015241974B2; BR112016022304B1; BR112016022304A2

Abstract

According to the present invention, provided is a water-containing bulk material treatment method, whereby the unloading disturbances on a belt conveyor due to slurry spring water that inevitably occurs at the time of unloading water-containing bulk material are eliminated by adding a flocculant to the water-containing bulk material at the junction or the like of the belt conveyor while the water-containing bulk material is carried to a cargo ship by the belt conveyor, and loading the water-containing bulk material, with the flocculant attached thereto, into the hold of the cargo ship.

Description

METHOD OF PROCESSING WATER-CONTAINING BULK MATERIAL AND APPARATUS FOR ADDING FLOCCULANT TO WATER-CONTAINING BULK MATERIAL

TECHNICAL FIELD

[0001] This disclosure relates to a method of processing a water-containing bulk material such as ore or coal containing water, whereby a flocculant is added to the water-containing bulk material at the time of loading at colliery in order to resolve defective unloading on a belt conveyor caused by free water during unloading of the water-containing bulk material from a carrier ship at the destination port. The disclosure also relates to an apparatus used for the method for adding a flocculant to a water-containing bulk material.

BACKGROUND

[0002] Bulk materials such as ore and coal are mainly imported from foreign countries, and mostly transported by ship (such as by an ore carrier, a coal carrier, or the like, which are simply referred to hereinafter as a “ship” or a “cargo ship”). Many of these bulk materials in recent years are high in water content, and are called water-containing bulk materials. Water separates from a water-containing bulk material and accumulates at the bottom of the ship’s hold during the transportation process.

[0003] Hence, in the middle or latter part of the unloading process using an unloader or the like, a free water suspension in which water is turbid with a powder occurs and accumulates in a depression formed after grabbing by a grab bucket for unloading (see FIG. 1), and the free water suspension eventually becomes slurry. This causes a problem of defective unloading. In FIG. 1, reference sign 1 is a hold, reference sign 2 is a water-containing bulk material, reference sign 3 is a free water suspension, reference sign 4 is a depression, reference sign 5 is an unloader, and reference sign 6 is a grab bucket.

The same problem arises in an unloading process using, for example, a bucket of a continuous unloader which includes a bucket conveyor and the like.

[0004] In view of this problem, for example, a method whereby when free water occurs, the free water is drawn up by a drainage unit (suction machine) and then unloading is resumed has been conventionally proposed, as disclosed in each of JP S60-204526 A (Patent Literature (PTL) 1) and JP S50-13339 Y (PTL 2). CITATION LIST Patent Literature

[0005] PTL 1: JP S60-204526 A PTL 2: JP S50-13339 Y PTL 3: JP S61-60784 A PTL 4: JP S61-164658 A

SUMMARY (Technical Problem) [0006] However, the drainage methods by drawing as proposed in PTL 1 and PTL 2 have a problem of long operation time as the ship needs to be moved to the location of the drainage (drawing) unit each time to draw up free water or the drainage (drawing) unit needs to be moved to draw up free water from the hold.

[0007] Since free water emerges in a depression formed after grabbing by a grab bucket during unloading, the free water drawing operation needs to be repeatedly performed in the above-mentioned drainage method by drawing. This necessitates repetitive stopping and resuming of the unloading operation, which is problematic in that the operation efficiency degreases significantly.

[0008] Particularly in recent years, such a problem is more evident because more and more ore and coal are of poor quality, e.g. high in water content. Moreover, when ore or coal has a high water content, the bulk material to be unloaded may easily develop a fluid state due to liquefaction even before free water occurs. If such a bulk material is unloaded, the unloaded bulk material tends to flow out of the belt conveyor because of its high fluidity. This hampers the conveyance of the bulk material. Thus, high fluidity of the bulk material on the belt conveyor frequently causes not only conveyance troubles, but also problems with the maintenance of the belt conveyor system.

[0009] The conventional techniques proposed in PTL 1 and PTL 2 are based on the assumption that only free water is drawn up. However, a powder with a small particle diameter separated from the bulk material with a large particle diameter flows into the depression formed after grabbing by the grab bucket, and mostly becomes slurry. The slurry liquid is difficult to be drawn by a conventional drainage unit, and furthermore, drawing operation is required each time free water occurs, worsening the operation efficiency. If such a bulk material is unloaded as-is, however, the bulk material tends to flow out of the belt conveyor because of its high fluidity as mentioned above. This also causes defective unloading.

[0010] To address these problems, we repeatedly performed research based on the water content reduction methods proposed in JP S61-60784 A (PTL 3) and JP S61-164658 A (PTL 4).

We as a result learned that the methods described in PTL 3 and PTL 4 have a problem in that, since a water-absorbent resin which is solid is used, it is difficult to bring the water-absorbent resin into uniform contact with the bulk material during unloading, and a problem in that the water-absorbent resin swells as a result of absorbing water and so tends to drop from the belt conveyor. The inventors also learned that, given that the water-absorbent resin needs to be eventually separated from the bulk material, it is very difficult, from a viewpoint of operation efficiency, to use the water-absorbent resin when unloading the water-containing bulk material.

[0011] Additionally, a water-containing bulk material high in water content tends to undergo liquefaction during sea transportation. Then, on board, when the water-containing bulk material reaches liquefaction, as shown in FIG. 2, the fluidized bulk material tends to be pushed to one side of the hold, shifting the balance of the ship, and, in the worst case, the ship will turn over beyond recovery.

[0012] In view of the above circumstances, it could thus be helpful to provide a method of processing a water-containing bulk material that can resolve defective unloading on a belt conveyor caused by slurry free water which inevitably occurs during unloading of a water-containing bulk material, and an apparatus used for the method for adding a flocculant to a water-containing bulk material. (Solution to Problem) [0013] To resolve the above problems, we investigated addition of a flocculant for solidifying water to a water-containing bulk material. As a result, we discovered that adding a flocculant to a water-containing bulk material at the time of loading at colliery so that the flocculant adheres to the bulk material is advantageous for resolving defective unloading. This disclosure was completed based on the discovery.

[0014] As illustrated in FIG. 3 as raw material at discharging port, free water 8 emerges between particles of a bulk material 7 during unloading of the water-containing bulk material. On the other hand, in the case of a water-containing bulk material at the time of loading at colliery, as illustrated in FIG. 3 as raw material at loading port, water 9 is trapped between particles of the bulk material 7. Accordingly, the addition of a flocculant at the time of loading at colliery may disturb uniform adhesion of the flocculant.

To prevent this, we further studied addition of a flocculant and discovered that artificially producing free water in a water-containing bulk material to cause diffusion of a flocculant is effective for adhering a flocculant to the bulk material. Our study also revealed that adding a flocculant in mist form is effective for facilitating diffusion of the flocculant. We further discovered that additionally performing a flocculant stirring or kneading step is effective for preventing non-uniform adhesion of a flocculant to the bulk material.

This disclosure was completed based on the above discoveries.

[0015] Specifically, the primary features of this disclosure are as described below. (1) A method of processing a water-containing bulk material such as ore or coal containing water, wherein when the water-containing bulk material is loaded onto a ship via a belt conveyor, a flocculant is added to the water-containing bulk material on the belt conveyor and/or at a junction part of the belt conveyor so that the flocculant adheres to the water-containing bulk material.

[0016] (2) The method of processing a water-containing bulk material according to (1), wherein when the flocculant is added, a flocculant diffusing liquid is further added.

[0017] (3) The method of processing a water-containing bulk material according to (1) or (2), wherein as the flocculant, a flocculating solution obtained by adding a flocculant diffusing liquid to a flocculant beforehand is added.

[0018] (4) The method of processing a water-containing bulk material according to any one of (1) to (3), wherein the addition of the flocculant is performed in mist spray form.

[0019] (5) The method of processing a water-containing bulk material according to any one of (1) to (4), wherein when the flocculant is added, the water-containing bulk material is stirred.

[0020] (6) The method of processing a water-containing bulk material according to any one of (1) to (5), wherein after the flocculant is added, the water-containing bulk material is stirred.

[0021] (7) An apparatus, used for the method of processing a water-containing bulk material according to any one of (1) to (3), for adding a flocculant to a water-containing bulk material, the flocculant being an additive selected from any one of a flocculant, a flocculant and a flocculant diffusing liquid, or a flocculating solution obtained by adding a flocculant diffusing liquid to a flocculant beforehand, the apparatus comprising: an addition unit configured to add the additive to the water-containing bulk material; an addition amount controller configured to control the addition amount of the additive; a sensor configured to collect information to determine when to start and stop the addition of the additive; and a tank configured to store the additive; and a conveyance hose configured to convey the additive from the tank to the addition unit.

[0022] (8) An apparatus, used for the method of processing a water-containing bulk material according to (4), for adding a flocculant to a water-containing bulk material, the apparatus comprising: an addition unit configured to spray a flocculant in mist form to the water-containing bulk material; an addition amount controller configured to control the addition amount of the flocculant; a sensor configured to collect information to determine when to start and stop the addition of the flocculant; a tank configured to store the flocculant to be added; and a conveyance hose configured to convey the flocculant from the tank to the addition unit.

[0023] (9) The apparatus for adding a flocculant to a water-containing bulk material according to (7) or (8), wherein the addition unit comprises a straight type nozzle or a three-way type nozzle.

[0024] (10) The apparatus for adding a flocculant to a water-containing bulk material according to any one of (7) to (9), wherein the addition amount controller comprises a pump.

[0025] (11) The apparatus for adding a flocculant to a water-containing bulk material according to (10), wherein the addition amount controller further comprises a valve and a nozzle distance adjuster.

[0026] (12) The apparatus for adding a flocculant to a water-containing bulk material according to any one of (7) to (11), wherein the sensor comprises a movable plate and a limit switch.

[0027] (13) An apparatus, used for the method of processing a water-containing bulk material according to (5) or (6), for adding a flocculant to a water-containing bulk material, the apparatus comprising: an addition unit configured to add a flocculant to the water-containing bulk material; and a mixing unit for stirring or kneading, wherein the addition unit comprises an addition amount controller configured to control the addition amount of the flocculant, and is installed either on a flocculant conveyor upstream of a point where the flocculant is charged to the mixing unit, or on the mixing unit. (Advantageous Effect) [0028] According to the disclosure, since the flocculant adheres to the bulk material beforehand, water will not separate from the bulk material in the hold of a cargo ship. This prevents the occurrence of free water during unloading, which would otherwise occur in conventional operation. The unloading operation can be continuously performed without being stopped, unlike with the conventional techniques, which contributes to improved unloading efficiency.

According to the disclosure, it is also possible to prevent the occurrence of an accident caused by a water-containing bulk material undergoing liquefaction during sea transportation, shifting the balance of the ship, and eventually causing the ship to turn over.

BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In the accompanying drawings: FIG. 1 illustrates unloading of a bulk material in a cargo ship using a grab bucket of an unloader; FIG. 2 illustrates a situation where a water-containing bulk material comes to liquefaction in a cargo ship; FIG. 3 illustrates water in a water-containing bulk material; FIG. 4 illustrates mine material management; FIG. 5 illustrates a situation where a water-containing bulk material including ore or coal is conveyed from a processing facility via a belt conveyer to a cargo ship; FIGS. 6A-B each illustrate an addition unit configured to add a chemical solution to a water-containing bulk material according to the disclosure; FIG. 7 illustrates an addition amount controller configured to control the addition amount of a chemical solution according to the disclosure; FIG. 8 illustrates four operation patterns implemented by an apparatus according to the disclosure; FIG. 9 illustrates a sensor having a movable plate and a limit switch; FIG. 10 is a flowchart of control implemented by the apparatus according to the disclosure; and FIGS. 11A-E are conceptual diagrams, each illustrating an action that occurs when a polymer flocculant is added to a free water suspension.

DETAILED DESCRIPTION

[0030] Our method and apparatus will be described more specifically below with reference to the accompanying drawings.

As illustrated in FIG. 1, the following phenomenon is typically known. When unloading ore or coal (hereafter also referred to as “ore(s)”) called a bulk material 2 stored in a cargo ship’s hold (cargo chamber) 1 with use of a bucket of a bridge crane or unloader 5 or continuous unloader, a pool of water resulting from water in the bulk material forms in the lower part of the ore deposit. When the unloading operation progresses and reaches the middle to lower parts of the ore deposit, a depression 4 is formed in part of the bulk material deposit. A free water suspension 3 in which a powder separated from the ore mainly in gravel form is dispersed and suspended accumulates in the depression 4.

[0031] The free water suspension 3 that emerges in the deposit of the water-containing bulk material 2 in the hold 1 gradually becomes slurry as the unloading progresses, making the unloading by the grab bucket 6 of the unloader 5 or the like difficult. This is because, once the slurry has formed, even if the slurry can be grabbed by the grab bucket 6, it flows out of a hopper (not illustrated) or a belt conveyer part (also called hereinafter a “BC,” not illustrated) in the unloader, as a result of which the operation of the unloader cannot be continued. Particularly at the bottom (lower part) of the hold 1, the free water suspension easily becomes slurry, and the unloading operation needs to be frequently stopped to perform drainage.

[0032] To prevent the occurrence of a free water suspension as stated above, this disclosure is characterized in that a flocculant is added to a water-containing bulk material at source colliery prior to loading onto a cargo ship, so that the flocculant adheres to bulk material particles in the water-containing bulk material prior to loading into the hold of the cargo ship.

[0033] FIG. 4 illustrates mine material management where ore is excavated at a mine site, loaded onto a vessel 13 or the like, delivered to a processing facility 14 where the ore is crushed to have predetermined components and particle size. After the processing, as illustrated in FIG. 5, the ore is transported on a belt conveyer or the like to a cargo ship such as an ore carrier or a coal carrier, and loaded.

[0034] According to the disclosure, in this stage a flocculant is added to a water-containing bulk material on the belt conveyer and/or at a junction part (including the inside of a connecting hopper) of the belt conveyer so that the flocculant adheres to the water-containing bulk material, and the water-containing bulk material is loaded into the hold of the cargo ship. In FIG. 4, reference sign 11 is a hydraulic excavator, reference sign 12 is an automotive vehicle, reference sign 13 is a vessel, reference sign 14 is a processing facility, and reference sign 15 is a hopper.

Such addition operation may cause a water-containing bulk material 2 and a free water suspension 3, more precisely, the components of the free water suspension 3, to assume a solid state (floe) in the end, enabling the conveyance of the water-containing bulk material together with water contained therein in unloading operation, and improving the unloading efficiency by preventing interruptions of the unloading operation. Note that the addition of the flocculant may be performed at at least one or more positions selected from in a connecting hopper, at a junction part of a BC, or on a BC.

[0035] According to the disclosure, for the addition of the flocculant, a flocculant diffusing liquid may be further added to the flocculant, a flocculating solution that is obtained by adding a flocculant diffusing liquid to a flocculant beforehand may be added as the flocculant, or the addition of the flocculant may be performed in mist spray form.

[0036] [Flocculant diffusing liquid]

Examples of the flocculant diffusing liquid used in the disclosure include water and organic solvents. Organic solvents include hydrocarbon-based solvents (containing only C, H, and O).

[0037] Assuming the flocculant diffusing liquid being water, the flocculant diffusing liquid (water) and the flocculant form coagulated particles, and the amount of water in the water-containing bulk material that emerges as free water does not increase.

[0038] [Mist spray form]

Mist spray form usable in the disclosure is spray nozzle form whereby the flocculant, whether in powder or liquid form, can be sprayed in mist form.

[0039] Moreover, when the flocculant is added to the water-containing bulk material, or after the flocculant is added to the water-containing bulk material, the flocculant and the water-containing bulk material may be stirred or kneaded together using a stirring or kneading unit, which will be described later, so that the flocculant adheres to the water-containing bulk material, and the resultant may be loaded onto a cargo ship.

[0040] In addition, the above-mentioned methods of processing a water-containing bulk material where the addition of the flocculant is performed at the selected position(s), for example, on a BC, may be carried out in combination as deemed appropriate.

[0041] [Flocculant]

In this disclosure, a flocculant mainly composed of a polymer flocculant (also called hereinafter a “chemical solution”) is used.

The polymer flocculant may be any polymer flocculant that has an adsorption activity on a powder and induces an inter-powder crosslinking action by the electrostatic force or hydrogen bond of the polymer, and has the effect of forming a solid granulated structure to generate coagulated particles (floe). For example, flocculants of polyacrylamide (copolymer of acrylamide and sodium acrylate), polyvinyl amidine, or an amphoteric polymer, which are powdery, granular, or liquid organic flocculants, are preferable as they exhibit not only the coagulation action but also the flocculation action. A well-known inorganic flocculant may also be mixed together.

As the polymer flocculant, an acrylate cationic polymer, an acrylamide cationic polymer, a methacrylate polymer, a methacrylate amino ester cationic polymer, an amidine polymer, an anionic W/O emulsion polymer, and the like are also available.

[0042] As used herein, the chemical agent mainly composed of a polymer flocculant refers to a chemical agent that contains the polymer flocculant at least in an amount commonly recognized to have the flocculation effect, and typically contains about 40 % or more of the polymer flocculant. Of course, a 100 % polymer flocculant may be used as the chemical agent. In this disclosure, the % representations are in mass%, except for the free water ratio and unless stated otherwise.

If the flocculant is in solid or liquid form and diluted in use, the solution includes water and an organic solvent, the solute includes a polymer of C, H, N, and O, and the solvent includes a hydrocarbon-based solvent (containing only C, H, O).

[0043] Additionally, the addition amount of the flocculant as used herein is preferably from 0.04 % to 1 % by dry mass with respect to the water content of the bulk material.

When the addition amount is within this range, the fluidity due to excess water decreases, and an increase in the viscosity due to excessive addition of the flocculant is prevented, as confirmed in the below-mentioned test results. The addition amount is more preferably 0.06 % to 0.4 % by dry mass with respect to the water content of the bulk material. As used herein, the addition ratio (amount) of the chemical solution is the ratio to the water content of the bulk material as mentioned above.

The addition rate of the flocculant is not particularly limited, and may be set as appropriate for the unit used and the like. As an example, the addition rate is about 2 L/min to 10 L/min.

[0044] While the disclosure has been made using Carajas iron ore as an example, other ores may also be used so long as they conform to the conditions of the present invention. In the case of using new iron ore, the target value of the water content can be determined by subjecting the new iron ore to the experiments such as the first and second experiments mentioned above.

To minimize the possibility that the free water-derived contained water overflows from the belt conveyer, it is safe to apply the present disclosure when the water-containing bulk material has a water content of 9.6 % or more. Note that a water-containing bulk material with a water content of more than 23 % is preferably mixed with a water-containing bulk material with a lower water content to have a water content of 23 % or less. As used herein, the water content (amount) is the ratio of the amount of water to the mass of the bulk material.

[0045] In addition, the disclosed apparatus may be an apparatus for adding an additive to a water-containing bulk material containing ores on a conveyance path as illustrated in FIG. 5, i.e., when conveyed from the processing facility 14, in which ore is crushed to predetermined components and particle size, via a belt conveyer or the like into the hold of a cargo ship. The additive may be selected from any one of a flocculant, a flocculant and a flocculant diffusing liquid, or a flocculating solution obtained by adding a flocculant diffusing liquid to a flocculant beforehand.

The apparatus is characterized by comprising: an addition unit configured to add an additive or spray a flocculant in mist form to the water-containing bulk material; an addition amount controller configured to control the addition amount of the additive; a sensor configured to collect information to determine when to start and stop the addition of the additive and the like; a tank configured to store the additive and the like to be added; and a conveyance hose configured to convey the additive and the like from the tank to the addition unit.

[0046] [Addition unit configured to add an additive to the water-containing bulk material]

The disclosed addition unit configured to add a chemical solution to the water-containing bulk material comprises: as illustrated in FIGS. 6A-B, a joint portion between the addition unit and a conveyance hose; a pipe; and a nozzle portion configured to spray liquid. As these components, any components may be used without limitation that are generally used for spraying of liquids and that enables addition of a predetermined amount of a chemical solution to a water-containing bulk material during conveyance to a cargo ship. A most preferred nozzle is a straight type nozzle as illustrated in FIG. 6A, or a three-way type nozzle as illustrated in FIG. 6B. In FIGS. 6A-B, reference sign 61 is a conveyance hose, reference sign 62 is a joint portion between the addition unit and the conveyance hose, reference sign 63 is a pipe, reference sign 64 is a straight type nozzle, reference sign 65 is a three-way type nozzle, and reference sign 66 is a corridor.

[0047] [Addition unit in mist spray form]

The disclosed addition unit may operate in mist spray form.

Specifically, the addition unit preferably operates in spray nozzle form.

[0048] Moreover, the addition unit may be installed at at least one or more positions selected from in a BC-connecting hopper, at a junction part of a BC, or on a BC.

[0049] [Addition amount controller configured to control the addition amount of the additive]

In this disclosure, the addition amount controller configured to control the addition amount of the additive preferably comprises, as illustrated in FIG. 7, a nozzle distance adjuster; a valve; and a pump for feeding liquid. In FIG. 7, reference sign 71 is a tank, reference sign 72 is a pump, reference sign 73 is a hose, reference sign 74 is a sensor, reference sign 75 is a valve, reference sign 76 is a distance adjuster, and reference sign 77 is a nozzle portion.

The addition amount control disclosed herein for controlling the addition amount of the additive may be performed using a valve by adjusting the degree of opening. Additionally, the amount of the additive added to ores may be controlled by, for example, adjusting the amount of the chemical solution discharged from the pump, changing the degree of opening at the tip of the nozzle, changing the number of nozzles, and adjusting the distance between ores and nozzles using the nozzle distance adjuster. Note that the addition amount controller is equally applicable to the operation form in which the flocculant is sprayed in mist form.

[0050] While the addition amount of the additive may be determined by experiments tailored to the characteristics of ores, it is desirable to set the addition amount to about 50 kg/h to 600 kg/h by dry weight for about 500 ton/h to 2000 ton/h.

[0051] The valve may be of any type commonly used on the conveyance path for conveying the additive. The nozzle distance adjuster may be a mechanism for raising and lowering the addition unit configured to add the chemical solution to the water-containing bulk material, a mechanism for expanding and contracting the pipe located between the nozzle portion and the joint portion between the addition unit and the conveyance hose, or the like. The pump, the valve, and the nozzle distance adjuster are not necessary components, but may be used selectively, or may not be used depending on the addition amount of the additive and the like.

[0052] As illustrated in FIG. 7, the disclosed apparatus comprises: a tank configured to store an additive to be added; and a conveyance hose configured to convey the additive from the tank to the addition unit. Any structural materials may be used that allows for storage and conveyance of the additive according to the type and amount required. The capacity of the tank and the diameter of the conveyance hose may be selected as appropriate for the unit size, the amount of the bulk material to be conveyed, and so on. The tank and conveyance hose are equally applicable to the operation form in which the flocculant is sprayed in mist form.

[0053] [Sensor configured to collect information to determine when to start and stop the addition of the additive]

The disclosed apparatus needs to operate in four patterns illustrated in FIG. 8. In the drawing, Pattern lisa pattern where addition of the additive needs to be performed, a BC used for addition of the additive is in operation, and a load is placed on the BC (as shown by icon).

Pattern II is a pattern where addition of the additive needs to be stopped, a BC used for addition of the additive is in operation, and no load is placed on the BC (as shown by icon).

Pattern III is a pattern where addition of the additive needs to be stopped, a BC used for addition of the additive is stopped, and a load is placed on the BC (as shown by icon).

Pattern IV is a pattern where addition of the additive needs to be stopped, a BC used for addition of the additive is stopped, and no load is placed on the BC (as shown by icon).

[0054] To ensure the functioning of the above-mentioned four operation patterns, and to verify if the motor of the BC is in operation and if any free water-containing ores are conveyed on the BC, it is necessary for the disclosed apparatus to have a sensor configured to collect information to determine when to start and stop the addition of the additive. The sensor preferably comprises a movable plate and a limit switch. This is because such set-up enables more precise detection of loads on the BC as illustrated in FIG. 9. Whether the motor of the BC is in operation may be determined from an electric signal indicative of on/off state of the motor that is obtained directly from the motor, or from an electric signal sent from the electric room. In FIG. 9, reference sign 91 is a movable plate and reference sign 92 is a limit switch.

[0055] It is important that if the addition unit configured to add the additive to the water-containing bulk material is installed on a BC, the sensor is installed on another BC upstream of that BC.

[0056] Whether ores on a BC are accompanied with free water can be visually determined by the operator, yet may be determined by measurement of the angle of repose of the material on the BC, by analysis of video images of material surfaces, or by automatic analysis of the material automatically collected on the BC. As used herein, the sensor configured to collect information to determine when to start and stop the addition of the additive is intended to encompass such features.

[0057] It is important that the actual control flow determines on/off state of the BC on a preferential basis as illustrated in FIG. 10. If the chemical solution is added when the BC is in off state, or stopped, the chemical solution accumulates under the BC due to its high viscosity, causing a unit failure. If the chemical solution is added when the BC is in on state, or in operation, with no load thereon, the BC may suffer rubber degradation and, again, a unit failure is caused by the chemical solution accumulating under the BC. The sensor is equally applicable to the operation form in which the flocculant is sprayed in mist form.

[0058] Additionally, the apparatus used for the method disclosed herein may comprise: an addition unit configured to add a flocculant to the water-containing bulk material; and a mixing unit for stirring or kneading, wherein the addition unit may comprise an addition amount controller configured to control the addition amount of the flocculant, and may be installed either on a flocculant conveyor upstream of a point where the flocculant is charged to the mixing unit, or on the mixing unit.

[0059] [Mixing unit for stirring or kneading]

As the mixing unit for stirring or kneading used for the disclosed method, any well-known and widely-used mixing unit that enables mixing of powder may be used.

[0060] [Addition unit configured to add a flocculant to the water-containing bulk material]

The addition unit used in the apparatus having the mixing unit may be the same as described in paragraph 0046.

[0061] [Addition amount controller configured to control the addition amount of the flocculant]

The addition amount controller may be the same as described in paragraph 0049.

[0062] [Principle for conveyability] FIG. 11A-B each illustrate water Wm contained in a free water suspension that includes a powder (bulk material) P, and a polymer flocculant A to be added thereto. When A is added to P, part of Wm and P coagulates as if caught by polymers B with dendritic molecular chains in the polymer flocculant A as illustrated in FIG. 11C, and forms some coagulated particles 21 small in particle diameter as illustrated in FIG. 11D. Subsequently, some coagulated particles 21 eventually flocculate (clump together) and grow into a flocculated particle 22 large in particle diameter as illustrated in FIG. 11E. Accordingly, by the expression “the flocculant adheres to the water-containing bulk material” used herein is meant not only a state in which the flocculant alone adheres to the water-containing bulk material, but also a state in which the flocculant and the flocculant diffusing liquid adhere to the water-containing bulk material, a state in which the above-mentioned flocculated particles and/or coagulated particles adhere to the water-containing bulk material, or a combination thereof. As used herein, the floe of the water-containing bulk material is made up of the flocculated particles and coagulated particles at any ratio (either of them may be 100 %).

[0063] In the stage illustrated in FIG. 11E, Wm has been solidified and is in an adhesion state of adhering to the bulk material. In this state, the bulk material can be easily conveyed on the belt conveyor, and the free water suspension itself can be conveyed together with the bulk material without overflowing from the belt conveyor. As a result, the bulk material can be delivered to a raw material yard or the like without any trouble.

Moreover, the components, such as N, C, and H, of the chemical solution as the flocculant disclosed herein are burned off by a sintering machine during the subsequent sintering step and do not remain in the product, eliminating the need for separation of the chemical solution. The present disclosure is thus advantageous in that a chemical solution separation step is unnecessary.

[0064] As mentioned earlier, when a water overflow occurs, the water or powder adhering to the back of the belt conveyor not only hampers the conveyance of the bulk material and the like, but also causes a failure of the conveyor rollers and the drive system. According to the disclosure, however, water and the bulk material are kept from overflowing from the belt conveyor, so that these problems can be effectively prevented even when conveying the bulk material with a high water content.

EXAMPLES

[0065] [Example 1]

The following experiment was performed, simulating a method of adding a flocculant to a water-containing bulk material conveyed on a belt conveyor.

The occurrence of free water was examined using Carajas iron ore (hereinafter “iron ore”) with a water content of 12 % to 24 % following the procedure below. (1) Iron ore was prepared in an amount of 30 kg, and dried by a dryer. After being dried, the iron ore was transferred to a container. (2) Water and a chemical agent were added to the iron ore transferred to the container to obtain a predetermined water content, and the resultant was stirred using a mixing stirrer. As the chemical agent (flocculant), Kurisat C-333L was used. Note that Kurisat C-333L is a liquid. (3) Upon completion of stirring, the container was covered to prevent water from evaporating, and left to stand for 24 hours. (4) After 24 hours, the container was subjected to vibration for 24 hours to simulate cargo ship transportation (rolling). (5) Then the mass of free water occurred was measured.

The experimental results are listed in Table 1. The evaluation results in the table are based on free water ratio (%). Free water ratio (%) is given by the equation below. free water ratio (%) = the amount of free water (kg) / the amount of water added (kg) x 100 [0066] [Table 1]

Table 1

[0067] The experimental results revealed that our examples all showed a lower free water ratio than Experiment Nos. 1 to 4 with a corresponding water content, to which no flocculant was added. In particular, for water content from 12 % to 20 %, no free water occurred (free water ratio: 0 %).

[0068] [Example 2]

An experiment was conducted in the same way as described in Example 1, except that the chemical agent was diluted with water at different conditions before being added to iron ore to facilitate diffusion of the chemical agent.

[0069] The experimental results revealed that the occurrence of free water after vibration test was effectively reduced when the chemical agent was diluted with water to a mass ratio (water/chemical agent) from 20 to 200 before being added to fine ore.

For a mass ratio (water/chemical agent) after the dilution of 10, the chemical agent was not, at least in part, sufficiently diffused in the target ore. On the other hand, for a mass ratio (water/chemical agent) after the dilution of 300, some of the added water emerged as free water. In either case, namely where the mass ratio was 10 or 300, the occurrence of free water during unloading was not so significant that it would interrupt the conveyance process.

In the experiment presented in Table 2, the chemical agent was added to a concentration of 0.4 % of the total of the diluting water and the water contained in ore itself.

[0070] [Table 2]

Table 2_

INDUSTRIAL APPLICABILITY

[0071] The method of processing a water-containing bulk material and the apparatus for adding a flocculant to a water-containing bulk material according to the disclosure can be applied to operations of conveying bulk materials that include not only water-containing ore or coal mentioned above but also gravel, sand, grain, and the like.

REFERENCE SIGNS LIST

[0072] 1 hold 2 bulk material 3 free water suspension 4 depression 5 unloader 6 grab bucket 7 bulk material 8 free water 9 water content of water-containing bulk material 11 hydraulic excavator 12 automotive vehicle 13 vessel 14 processing facility where ore is crushed to have predetermined components and particle size 15 hopper 21 small coagulated particle 22 large flocculated particle 61 conveyance hose 62 joint portion between addition unit and conveyance hose 63 pipe 64 straight type nozzle 65 three-way type nozzle 66 corridor 71 tank 72 pump 73 hose 74 sensor 75 valve 76 distance adjuster 77 nozzle portion 91 movable plate 92 limit switch A polymer flocculant B polymer P powder

Wm water

Claims

1. A method of processing a water-containing bulk material such as ore or coal containing water, wherein when the water-containing bulk material is loaded onto a ship via a belt conveyor, a flocculant is added, on the belt conveyor and/or at a junction part of the belt conveyor, to the water-containing bulk material so that the flocculant adheres to the water-containing bulk material.

2. The method of processing a water-containing bulk material according to claim 1, wherein when the flocculant is added, a flocculant diffusing liquid is further added.

3. The method of processing a water-containing bulk material according to claim 1 or 2, wherein as the flocculant, a flocculating solution obtained by adding a flocculant diffusing liquid to a flocculant beforehand is added.

4. The method of processing a water-containing bulk material according to any one of claims 1 to 3, wherein the addition of the flocculant is performed in mist spray form.

5. The method of processing a water-containing bulk material according to any one of claims 1 to 4, wherein when the flocculant is added, the water-containing bulk material is stirred.

6. The method of processing a water-containing bulk material according to any one of claims 1 to 5, wherein after the flocculant is added, the water-containing bulk material is stirred.

7. An apparatus, used for the method of processing a water-containing bulk material according to any one of claims 1 to 3, for adding a flocculant to a water-containing bulk material, the flocculant being an additive selected from any one of a flocculant, a flocculant and a flocculant diffusing liquid, or a flocculating solution obtained by adding a flocculant diffusing liquid to a flocculant beforehand, the apparatus comprising: an addition unit configured to add the additive to the water-containing bulk material; an addition amount controller configured to control the addition amount of the additive; a sensor configured to collect information to determine when to start and stop the addition of the additive; and a tank configured to store the additive; and a conveyance hose configured to convey the additive from the tank to the addition unit.

8. An apparatus, used for the method of processing a water-containing bulk material according to claim 4, for adding a flocculant to a water-containing bulk material, the apparatus comprising: an addition unit configured to spray a flocculant in mist form to the water-containing bulk material; an addition amount controller configured to control the addition amount of the flocculant; a sensor configured to collect information to determine when to start and stop the addition of the flocculant; a tank configured to store the flocculant to be added; and a conveyance hose configured to convey the flocculant from the tank to the addition unit.

9. The apparatus for adding a flocculant to a water-containing bulk material according to claim 7 or 8, wherein the addition unit comprises a straight type nozzle or a three-way type nozzle.

10. The apparatus for adding a flocculant to a water-containing bulk material according to any one of claims 7 to 9, wherein the addition amount controller comprises a pump.

11. The apparatus for adding a flocculant to a water-containing bulk material according to claim 10, wherein the addition amount controller further comprises a valve and a nozzle distance adjuster.

12. The apparatus for adding a flocculant to a water-containing bulk material according to any one of claims 7 to 11, wherein the sensor comprises a movable plate and a limit switch.

13. An apparatus, used for the method of processing a water-containing bulk material according to claim 5 or 6, for adding a flocculant to a water-containing bulk material, the apparatus comprising: an addition unit configured to add a flocculant to the water-containing bulk material; and a mixing unit for stirring or kneading, wherein the addition unit comprises an addition amount controller configured to control the addition amount of the flocculant, and is installed either on a flocculant conveyor upstream of a point where the flocculant is charged to the mixing unit, or on the mixing unit.