JPS584670B2 - Marine transportation method for slurry - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for loading slurry into an inboard tank, transporting it by sea, and unloading it.

Traditionally, the common method for transporting kaolin by sea, which is used as a raw material for paper manufacturing, is to package powdered kaolin in bags and load it onto a ship. In addition to the drying fuel and bagging materials required to obtain the kaolin powder,
May cause dust pollution.

Conventionally, kaolin has been made into a slurry, stored in containers, and transported on container ships, but even with this method, a large number of specialized containers are required, the handling of which is complicated, and transportation costs are high. There is a problem in that it is not possible to reduce the

The present invention aims to solve the above-mentioned problems associated with marine transportation of slurry such as kaolin slurry, and provides a method for efficiently transporting and unloading a large amount of slurry by sea while maintaining its quality. The purpose is to provide.

For this reason, the marine transport cargo handling method for slurry of the present invention is such that the slurry is loaded into a tank onboard a ship at a loading port and transported by sea, and then the slurry is transported at a loading port to a place where the slurry is deposited at the bottom of the tank. The cargo is unloaded overboard using an inboard pump through the loading port located above, and then slurry is injected onto the precipitate that has settled at the bottom of the tank to form a slurry. The ship is characterized in that the slurry-formed sediment is unloaded by an inboard pump while selectively using the arrayed loading ports.

Further, in the marine transport cargo handling method for slurry of the present invention, when the slurry is injected onto the precipitate that has settled at the bottom of the tank at the unloading port, a trim operation that becomes a bow trim is performed to create an exposed surface on the precipitate. The slurry is injected onto this exposed surface to promote the slurrying of the precipitate, and the slurry is then slurried while selectively using the loading ports arranged vertically near the bottom of the tank. The ship is characterized by unloading using an onboard pump.

Hereinafter, a marine transport cargo handling method for slurry as an embodiment of the present invention will be explained with reference to the drawings. Fig. 1 is a graph showing an example of the relationship between the concentration and viscosity of kaolin slurry, and Figs. The figures up to the figures show an example of a slurry transport vessel used in the method of the present invention, with Fig. 2 being a longitudinal sectional view thereof, Fig. 3 being a cross sectional view thereof, and Fig. 4 being a slurry transport vessel installed in the slurry tank. FIG. 5 is a partial diagram showing a piping system diagram, and FIGS. 6 a to 6 i are explanatory diagrams showing the situation in which slurry precipitate is unloaded.

The method of the present invention includes, for example, preparing kaolin into a slurry,
Kaolin slurry is loaded onto a slurry transport ship as liquid cargo, transported by sea, and unloaded.The main properties expected of kaolin slurry from the point of view of sea transport are: (1) It should be as concentrated as possible, i.e. water content. (2) Low viscosity, which means it is easy to handle with a pump. (3) Good quality stability, which means that separation of kaolin particles and water is difficult, and there is little precipitation. ,
The goal is to maintain the properties of kaolin for a long period of time.

In order to prepare a kaolin slurry that satisfies these properties, it is first necessary to atomize kaolin particles during the refining process from kaolin raw stone.

An example of the particle size distribution of kaolin, which is purified and atomized and shipped as a product, is that the particle size of 2 microns or less is 8.
0 to 82% (by weight), and 3 to 6% having a particle size of 5 microns or more.

Approximately 70% of this atomized kaolin,
A kaolin slurry is prepared by mixing the mixture with approximately 30% fresh water by weight, adding a small amount of dispersant, and stirring the mixture in a high-speed mixer.

As the dispersant, for example, tetrasodium pyrophosphate is added in an amount of 0.1 to 0.5% of the kaolin.

The relationship between the concentration and viscosity of the kaolin slurry thus obtained is shown in FIG. 1, for example.

In Figure 1, the viscosity changes rapidly around 70% concentration, and at 70% concentration, the viscosity is 300 CP (centipoise).
However, if the concentration exceeds 72%, it is no longer a liquid and cannot be handled by a pump.

Also, if the concentration is set to 60%, the viscosity will drop to 70CP, making it easier to handle the cargo with a pump, but the lower the concentration, the less kaolin in the cargo being transported (carrying more wasteful water), which means more efficient transport. If the concentration is lower than 65%, the stability of the slurry is poor, and kaolin tends to separate from water during transportation, resulting in increased precipitation.

For this reason, it is desirable that the concentration of kaolin slurry used for sea transportation be as high as possible within the range that can be handled by pumps, and depending on the properties of the kaolin (degree of purification, particle size distribution, etc.), it is desirable that the concentration is as high as possible. % concentration is selected.

The specific gravity of the kaolin slurry at 70% concentration is approximately 1.8.

An example of a slurry transport vessel used in the method of the present invention is shown in the second example.
5 to 5, four slurry tanks 1 are provided in the longitudinal direction of the ship, and a pump room 2 is arranged on the stern side of each tank.

The slurry tank 1 is constructed as part of the hull structure by two longitudinal bulkheads 3, a transverse bulkhead 8, a deck 5, and a double bottom top plate 4.

Each stiffener is placed on the outer side of the slurry tank 1, and the inner surface of the slurry tank 1 is as smooth as possible without protrusions from the structure.The inner surface of this tank is coated with epoxy and made of kaolin. This prevents the slurry from being contaminated by iron rust.

It is also a good idea to line the slurry tank 1 with a stainless steel sheet instead of epoxy coating.

Further, reference numeral 6 indicates a ballast tank, and 7 indicates a stiffener with a deck.

In order to minimize the suction resistance of the highly viscous kaolin slurry, the slurry pumps are distributed and arranged in each pump room 2 adjacent to the slurry tank 1.

In addition, an appropriate number of loading ports 10 (three in the example shown in FIG. 4) are provided vertically at different heights at the bottom of the tank on the stern side of each slurry tank 1, and are connected to a slurry pump 13 through a valve 11 and a loading pipe 12. has been done.

During the transportation voyage of kaolin slurry, the surfaces that come into contact with the kaolin slurry near the loading port 10, the inner surface of the loading port 10, the main body of the valve 11, and the disks are all designed to prevent the metal skin from being exposed and coming into contact with the kaolin slurry. It is composed of

In this embodiment, these parts are made of metal material and covered with plastic, but this is a better method than making these parts of plastic material.

In the figure, reference numeral 14 indicates a discharge pipe, 15 indicates an outboard connection port, 16 indicates an injection liquid tank, 17 indicates an agitator, 18 indicates an injection pump, 19 indicates an injection nozzle, 20 indicates a loading pipe, and 21 indicates a valve.

The kaolin slurry prepared as described above on land is loaded into the slurry tank 1 through the outboard connection port 15 and the loading pipe 20 by a land pump at the loading port.

At this time, the valves 21 and 11 are closed to prevent the slurry from flowing into the discharge pipe 14, slurry pump 13, etc.

Once the kaolin slurry has been loaded into the tank 1 in this manner, the slurry is transported by sea without being subjected to operations such as dehydration or stirring.

Also, during the voyage, operations such as dehydration and stirring are not performed.

If the kaolin slurry is left standing without being stirred, kaolin particles will precipitate and accumulate at the bottom of the tank over time.

The amount of precipitate deposits varies greatly depending on the properties of kaolin (degree of purification, particle size distribution, etc.) and the slurry preparation method, but it is not possible to avoid more or less deposits of kaolin particles.

This kaolin precipitate has no fluidity, and if the loading port is buried in it, it will be impossible to suction and discharge the slurry from the loading port unless it is removed.

Therefore, a plurality of loading ports at the bottom of the tank are installed at different heights, one above the other, so that at least one loading port is located above the kaolin precipitate at the start of unloading.

On the other hand, since the kaolin particles in the slurry have a negative charge, there are exposed metal parts at the loading port 10 and the valve 11, such as stainless steel, brass, cast iron, etc., which have a positive charge. If it is contaminated with kaolin, it will adsorb kaolin particles and cause problems such as valve opening/closing failure and loading/unloading port blockage.

For this reason, it is necessary to prevent the kaolin particles from being electrically adsorbed to the loading port, and as a countermeasure to this, in this embodiment, the metal members around the loading port are coated with plastic or epoxy paint.

After the ship docks at the unloading port, the kaolin slurry in the tank 1 is transferred to the external connection port 1 by using the slurry pump 13.
The cargo is unloaded through 5th.

FIGS. 6 a to 6 i are explanatory diagrams showing the conditions in which transported kaolin is unloaded, and in particular, the conditions in which slurry precipitate is unloaded.

FIG. 6a shows the state at the start of unloading, and the kaolin slurry 30 maintains a substantially homogeneous liquid state as a whole;
A precipitate 31 with no fluidity is deposited at the bottom of the tank.

Among the three loading ports 10, the one at the top is located above the surface layer of the sediment 31, and if the slurry above the sediment is sucked through this loading port and the cargo is unloaded while attaching the stern trim. The state shown in FIG. 6b is reached.

During unloading, a portion of the slurry is transferred to the injection liquid tank 16.
Store it in.

The transported slurry may be used as the injection liquid as it is, but if the concentration of the slurry is lowered by adding a small amount of water to the injection liquid tank 16 and stirring, the viscosity of the injection liquid will be greatly reduced, making it more efficient and efficient. Able to spray powerfully.

As an example, the graph in Figure 1 shows that a slurry with a concentration of 70% has a viscosity of 300 CP (centipoise), but if 20 tons of fresh water is added to 100 tons of slurry, the concentration becomes 58.3% and the viscosity is It is about 60 CP, which is about 1/5.

In this way, the slurry was drawn from the injection liquid tank 16, and the slurry was injected from the injection nozzle 19 onto the sediment 31 at the bottom of the tank 1 using the injection pump 18, thereby fluidizing the sediment 31 and injecting it. It is sucked together with the slurry by a slurry pump through the loading port 10 at the top and returned to the injection liquid tank 16.

At that time, a portion of the slurry is appropriately unloaded overboard and mixed with the slurry that has already been unloaded.

Eventually, the state shown in Fig. 6c is reached, and after the fluidization of the sediment no longer progresses, the bow trim and shear are brought into the state shown in Fig. 6d, due to the ballast operation.

When slurry injection is continued to fluidize the precipitate, a second loading port 10 eventually appears, through which the fluidized precipitate is sucked.

If the same operation is carried out while repeating slurry injection and trim changes as appropriate, all of the slurry precipitates can be unloaded through the states shown in Fig. 6 e, f, g, and hi.

Although the illustration of the onshore receiving tank is omitted, it is usually an upright cylindrical tank and is equipped with an agitation device to prevent sedimentation, so that the slurry is constantly agitated.

The injection liquid, together with the fluidized precipitate, is finally all discharged and mixed with the already discharged slurry.

Adding fresh water to the injection liquid will lower the overall concentration of the slurry, but for example, if the total amount of slurry is 10,000 tons, adding 20 tons of fresh water will reduce the concentration to 70.
% slurry becomes 69.86%, but this does not pose a practical problem.

As described in detail above, according to the marine transport cargo handling method for slurry of the present invention, operations such as dehydration and stirring are not required during slurry loading and transport voyage, and slurry is loaded into tanks using pumps and piping. In addition, at the unloading port, the slurry is unloaded overboard by an inboard pump through a loading port located above the sediment that has settled at the bottom of the tank, and is then transferred to the sediment that has settled at the bottom of the tank. The slurry is injected to turn the precipitate into a slurry, and the slurry-formed precipitate is unloaded by an inboard pump while selectively using loading ports arranged vertically near the bottom of the tank. In addition to making it possible to transport slurry economically by sea, the sediments generated during transport of slurry can be efficiently fluidized and unloaded, which allows cargo handling at the unloading port to be carried out quickly without any problems There are advantages to being able to do this.

Further, according to the method of the present invention, when injecting the slurry to the precipitate deposited at the bottom of the tank, a trim operation serving as a bow trim is performed to create an exposed surface in the precipitate, and the exposed surface is Since slurry is injected to promote slurry formation of the precipitate, all of the slurry precipitate can be unloaded, which has the advantage of greatly improving unloading efficiency.

[Brief explanation of the drawing]

Fig. 1 is a graph showing an example of the relationship between the concentration and viscosity of kaolin slurry, and Figs. 2 to 5 show an example of a slurry transport vessel used in the method of the present invention.
Fig. 2 is a longitudinal cross-sectional view, Fig. 3 is a cross-sectional view, Fig. 4 shows the arrangement of loading ports provided in the slurry tank, and Fig. 5 is a partial diagram showing a piping system diagram. , FIGS. 6 a to 6 i are explanatory diagrams showing the situation in which slurry precipitate is unloaded. 1...Slurry tank, 2...Pump room, 3.
...Longitudinal bulkhead, 4...Double bottom top plate, 5...Deck, 6
...Ballast tank, 7...Stiffener, 8...
Transverse bulkhead, 10... Loading port, 11... Valve, 12.
... Cargo handling pipe, 13... Slurry pump, 14... Discharge pipe, 15... Outboard connection port, 16... Injection liquid tank, 17... Stirrer, 18... Injection pump, 19・・・
- Injection nozzle, 20... Loading pipe, 21... Valve, 30... Kaolin slurry, 31... Slurry sediment.

Claims (1)

[Scope of Claims] 1. After loading the slurry into a tank onboard a ship at a loading port and transporting it by sea, the slurry is transferred to a loading port located above the precipitate that has settled at the bottom of the tank at the unloading port. The cargo is unloaded overboard using an inboard pump through the tank, and then slurry is injected onto the sediment that has settled at the bottom of the tank to form a slurry, and the loading ports arranged vertically near the bottom of the tank are A method for transporting and handling slurry by sea, which comprises selectively using the slurry and unloading the slurry by an inboard pump. 2. The slurry according to claim 1, wherein a part of the slurry lifted by the inboard pump is diluted and used as the slurry to be injected to the precipitate deposited at the bottom of the tank. sea transport cargo handling method. 3. At the loading port, the slurry is loaded into a tank on the ship and transported by sea. At the unloading port, the slurry is transferred to the ship using an onboard pump through a loading port located above the sediment that has settled at the bottom of the tank. When the cargo is unloaded outside and the slurry is injected onto the precipitate that has settled at the bottom of the same tank, a trim operation that will become the bow trim is performed to create an exposed surface on the precipitate, and the slurry is injected onto this exposed surface. to promote slurrying of the precipitate, and unload the slurry-formed precipitate with an inboard pump while selectively using loading ports arranged vertically near the bottom of the tank. A distinctive feature of the marine transportation and handling method for slurry.