GB2111659A

GB2111659A - Adjusting the quantity of liquid deposited on fine granular material

Info

Publication number: GB2111659A
Application number: GB08230550A
Authority: GB
Inventors: Yasuro Ito; Yoshiro Higuchi; Yasuhiro Yamamoto
Original assignee: Taisei Corp
Current assignee: Taisei Corp
Priority date: 1979-03-13
Filing date: 1982-10-26
Publication date: 1983-07-06
Also published as: FR2457166A1; FR2457166B1; GB2048446B; GB2111659B; FR2457165A1; CH649225A5; DE3009332A1; GB2048446A; FR2457165B1

Abstract

Liquid adhering to the surface of fine particles (e.g. sand) is removed by projecting the particles by a rotating member, such as a disc 2, and applying to the projected particles an impulsive force larger than the adhesive force of the liquid, by causing the particles to collide with a body, such as a ring 6. In this way at least part of the liquid is removed. <IMAGE>

Description

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GB 2111 659 A

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SPECIFICATION

Adjusting the quantity of liquid deposited on fine granular material

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This invention relates to a method and apparatus for adjusting the quantity of liquid, typically water, deposited on the surface of the particles fine granular material.

10 Fine aggregates comprising river or mountain sand or artificial fine particles are widely used to prepare cement mortar or limestone type hydraulic mortar which is used to construct buildings and many other civil engineering structures. When 15 digging or crushing various ores utilized in metallurgy or ceramic industry and coal, fine particles or duct are formed. Further, depending upon the field of use, it is necessary to crush the ores or coal into granules having a predetermined size. 20 When pulverizing or refining these substances or when using them for chemical reactions, fine granulates in the form of sludge or the like are often formed. As is well known, these fine granulates contain substantial quantity of water adhering to the 25 surface of the grains. This is true not only for river or mountain sand but also coal. Especially, in recent years these substances are excavated by using jet water so that the quantity of the deposited water is large. Even a converter slag, which is free from water 30 when it is formed, becomes wet when water is used to collect it. Moreover, as these materials are stored in the outdoor they are wetted by rain, dew, or snow. Such wet particles can not be used directly. For example, when sintering these materials or 35 converting them to coke, and even when they are directly charged in a furnace, it is necessary to preliminarily dry them before actual use. This requires extra heat energy, i.e. fuel.

When a fine aggregate composed of river or 40 mountain said is used for the preparation of mortar or cement, the quantity of the deposited or surface water is an important factor which influences the quality of the product. Although the composition and particle size of sand also influence the quality of 45 the product, so long as sand collected from the same source is used it is easy to utilized sand having the same composition and particle size, and it is rare to admix sands from different sources. When the sand contains particles of different size it is easy to 50 classify them into fine, medium, and coarse particles with a sieve, and a small difference in the particle size does not result in a great difference in the quality of the product. However, the quantity of the surface water varies greatly depending upon the 55 source and the methods of collecting, conveying, and storing the sand. Moreover, the specific surface area of the fine particles of sand is large, so that the relatively quantity of the deposited water is large. Moreover, sand contains water in the interstices of 60 the sand particles, which varies from time to time depending upon weather conditions. More particularly, when sand from the same source is piled up on the ground, its water content varies at the top and the bottom, and in the morning and at 65 noon.

When preparing cement mortar or concrete by using a fine aggregate, the ratio of water to cement (W/C), the ratio of cement to sand (C/S), and the ratio of sand orcementto gravel or other coarse aggregate (S/G orC/G) have a great influence upon the strength of the resulting product and on its fluidity, moldability, and workability. Thus, when an excessive quantity of water is incorporated, segregation and bleeding are inevitable, thus decreasing the mechanical strength of the product. On the other hand deficient water impairs moldability and pouring property, so that even when vibration or pressure is applied at the time of molding or pouring it is difficult to obtain a dense structure, and this also decreases the mechanical strength. As above described, notwithstanding the fact that it is essential to select adequate W/C etc., as the quantity of the deposited water varies greatly and as it is diffficult to simply and accurately measure the quantity of the surface water, it is difficult to realize ideal ratios W/C, S/C, etc. Although it has been proposed to completely dry the fine aggregate or to measure the weight thereof in water, such methods are not suitable in the field where a large quantity of sand is used. More particularly, the former method requires a large quantity of heat energy and time and the latter method requires a step of perfectly permeating the sand with water so as to drive off air (according to JIS (Japanese Industrial Standard) it is prescribed to immerse the sand in water for 24 hours) and a step of draining the water contained in the sand.

What is desired is a method and apparatus for quickly and accurately adjusting the quantity of water deposited on fine granular aggregate, whereby, for example, cement mortar or concrete of improved quality can be prepared by utilizing the fine aggregate with its quantity of surface water adjusted to a desired value.

According to one aspect of this invention there is provided a method of adjusting a quantity of liquid of deposited on fine particles, i.e. sand, comprising the steps successively supplying a predetermined quantity of the fine particles deposited with liquid, and then applying an impact force larger than the adhesive force of the liquid to the fine particles thereby removing the deposited liquid.

According to another aspect of this invention there is provided apparatus for separating liquid from fine particles comprising liquid separating meansfor applying a impulse force to the fine particles so as to remove excess liquid deposited on the particles and means for successively supplying the fine particles to the liquid separating means.

The impact force can be due to kinetic energy imparted by centrifugal force created by a rotating disc.

The invention is especially suitable to adjust the quantity of water on sand particles which are used to prepare cement mortar or a green concrete compound. The quantity of water remaining on the surface of the sand particles is used to determine the quantity of water to be subsequently added to a mixture of sand, gravel, and cement.

In the accompanying drawings:

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Fig. 1 is a longitudinal sectional view of a water separator;

Fig. 2 is a longitudinal sectional view showing a modified water separator;

5 Fig. 3 is a partial longitudinal sectional view showing a modification of the water separator shown in Fig. 2;

Fig. 4 is a side view of the water separator with auxiliary equipments;

10 Fig. 5 is a longitudinal sectional view showing the upper portion of a modified water separator;

Fig. 6 is a perspective view showing an impact frame shown in Fig. 5;

Fig. 7 is a plan view of the rotating disc shown in 15 Fig. 5 taken along a line VIII-VIII;

Fig. 8 is a sectional plan view taken along a line IX-IX in Fig. 5;

Fig. 9 is a side view, partly in longitudinal section, of another embodiment of the water separator; 20 Fig. 10 is a perspective view showing a manner of attaching a section of an impact surface;

Fig. 11 is an enlarged sectional view showing the relationship between the impact surface, a cleaning water tank, a water receiving tank, and a receptacle; 25 Fig. 12 is a partial sectional view showing means for removing deposited sand particles;

Fig. 13 and 14 show modified means for removing the deposited sand particles, which are simpler than that shown in Fig. 12;

30 Fig. 15 is a sectional view showing another embodiment of the water separator not utilizing a rotating disc;

Figs. 16,17,18,19 show still other modifications of the water separator;

35 Fig. 20 is a graph showing the result of water removal.

Before describing in detail with reference to the accompanying drawings, the principle and advantages of the invention will firstly be described. 40 Where excessive surface water is removed by heat or wind power it is not only difficult to accurately adjust the quantity of water deposited on the fine aggregate but also requires a large quantity of heat energy and time. As above described according to 45 this invention, the quantity of water is adjusted by applying an impact force or velocity energy to the fine aggregate but with this improved method the quantity of water that can be efficiently removed varies depending upon the quantity of water 50 originally contained. For this reason the impulse force applied to the sand must be determined depending upon the quantity of water originally contained. The impact force or shock can be applied by beating but it is more advantageous to apply it as 55 velocity energy. Where the quantity of the deposited water is relatively large, use of the velocity energy caused by gravity is effective to remove a certain amount of water. More advantageous velocity energy is that utilizing wind power, rotating force, or 60 centrifugal force. One or combinations of two or more of these velocity energies can be used. It is also possible to sprinkle the particles of the coarse aggregate by applying thereto the velocity energy of rotating force or centrifugal force to cause the 65 spinkled particles to collide against a surface to remove the surface water. Alternatively, while the particles are standstill or slowly dropping under gravity an impact force may be applied to cause the particles to collide againsta rotating body, in each 70 case, the surface water is transferred to the surface or body collided by the particles to adjust the quantity of water remaining on the surface thereof. Thus, the quantity of remaining water is inversely proportional to the strength of the impact force 75 whereby the quantity of the remaining water can be adjusted to a desired value by suitably selecting the strength ofthe impactforce. In other words, irrespective ofthe particle size (fine, medium, or coarse) of a fine aggregate which usually contain a 80 relatively small amount of water, for example 2 to 4%, the water can be removed adequately by using a suitable impactforce. Howeverthe quantity ofthe deposited water is large for example 7-8% or more, water beyond a certain limit can be removed by the 85 impact energy, the degree of removal being proportional to the impact energy. A fine aggregate whose quantity of deposited water varies in a relatively small range, for example from 2.5-6% is advantageous to determine the quantities of water 90 and cement to be incorporated subsequently. When the quantity ofthe water deposited on the particles of the fine aggregate is reduced or adjusted to a predetermined value, it is possible to readily obtain desired ratios of W/C, C/S, and G/S, thus ensuring 95 uniform quality ofthe resulting product.

From the standpoint of cost of installation and operating power, it is advantageous to cause the particles ofthe fine aggregate to collide against a stationary surface by using a rotating disc in which 100 case the particles are supplied to the central portion ofthe disc to cause them to fly by centrifugal force. The sand often contains mud or clay which deposit on the surface ofthe sand particles, and in an extreme case the layer ofthe deposited mud or clay 105 bonds together the particles ofthe fine aggregate colliding thereupon to increase the thickness ofthe layer. Further, the deposited layer acts as a cushion layer to decrease the impact force applied to the particles thereby varying the quantity of the 110 deposited water even with the same impactforce. In such a case it is necessary to clean the stationary surface with water or with a rotating wiper or by rotating the surface.

In cold season, water containing sand freezes, in 115 which case the sand is defrozen with steam to separate its particles. When sea sand is used salt contained therein be removed when the quantity of the deposited water is reduced by the method of this invention.

120 A preferred separator shown in Fig. 1 comprises a hopper 1, a rotating disc 2 disposed beneath the hopper 1. The rotary disc 2 is provided with a central opening 12 to receive the fine aggregate from the hopper and a plurality of radial vanes 7. The rotary 125 disc 2 is supported by a rotatable sleeve 13 supported by a stationary sleeve 14through bearings 3. The sleeve 13 is rotated by an electric motor 4 through pulleys 5 and 15 and a belt passing about these pulleys. An annular ring 6 is disposed to 130 surround the rotary disc 2 with a suitable distance

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therebetween, the annular ring being detachably mounted on the inner side of a lower frust conical hollow casing 10. Funnel shaped receiver 8 is contained in the lower portion ofthe lowercasing 10 5 with a suitable gap therebetween. Adjacent the discharge opening 18 at the lower end ofthe receiver 8 is disposed a conveyor 11 for receiving the fine aggregate which falls down after collision against the annular ring 6. The annular ring is 10 slightly inclined, and if desired its upper edge may be bent inwardly for preventing upward sprinkling of the sand particle. With this construction vanes 7 may be omitted. By increasing the inclination angle ofthe annular ring the collection ofthe sand particles by 15 the receiver 8 can be improved. A water spray pipe 16 is provided at the lower end ofthe hopper 1 and if desired a screw type or ribbon type agitator may be provided at the lower end ofthe hopperto uniformly apply a suitable quantity of water to the sand 20 particles. The water separated by the collision against the annular ring falls down as shown by dotted line arrows to the bottom ofthe lower casing 10.

Fig. 2 shows a modified water separator A utilized 25 in this invention in which the relative arrangement of the hopper 1, rotating disc 2, the motor 4, the sleeve 13, and the motor 4 is generally similar to that ofthe first embodiment. However, the annular ring or impact plate 6 against which the sand particle are 30 ejected by the centrifugal force created by the rotating disc 2 is interposed between separated upper portions of a bell shaped receiver 10 and reinforced by an outer ring 18a secured to the annular ring by screws 19. This construction allows 35 ready exchange ofthe annular ring 6. The lower end 20 is bulged outwardly to receive the upper end of a receptacle 9 supported by a frame 22. A small gap is defined between the upper end ofthe receptacle 9 and the bulged out end 20 to permit passage ofthe 40 separated water, whereas dehydrated sand particles fall down into the receptacle.

Although not shown in Fig. 2, it should be understood that a conveyor is installed beneath the receptacle in the same manner as in Fig. 1 to convey 45 the sand particles.

The casing 10 of the water separator shown in Fig. 2 may be modified as shown in Fig. 3 and various auxiliary equipments may be provided as shown in Fig. 4. Thusfas shown in Fig. 3, a plurality of 50 telescoped annular members 9a and 9b connected by connecting members 31 to the upper edge member 9c of the receptacle 9 are disposed within the annular ring 6. The upper ends of respective annular members 9a, 9b, and 9c are sharped to 55 define a passage for passing air and watertogether with the inner surface ofthe casing 10. These knife edge shaped upper ends further function to deflect the sand particles moving along the inner surface of the casing 10 away therefrom toward the inside of 60 the receptacle 9.

An annular rotating disc 2a slightly inclined toward lower as shown by dotted lines may be attached to the rotating disc 2 for directing the sand particles to the lower side. With this construction the 65 projected sand particles are blasted against the lower portion ofthe annular ring 6 but a centrifugal force sufficient to separate the sand particles can be applied by the inclined auxiliary rotating disc 2a so that the vanes 7 may be omitted. In this case, the spacings between the annular members 9a, 9b and 9c and the casing 10 may be made smaller than those shown in Fig. 3.

When the water separator shown in Fig. 3 is operated under optimum operating conditions to be described later, the substance that flows downwardly along the inner surface ofthe casing consists essentially of water and mud which can be discarded.

However, optimum operating conditions are not always obtained depending upon the characteristic ofthe sand particles. In such as case, the substance falling to the outside ofthe receptacle 9 through a gap between the lower inner surface ofthe casing 10 and the knife edge shape portion 9c is separated into water, mud and sand particles which can be recharged into the hopper 1 by a conveyor or the like. The water component separated by the water separator may be used to prepare concrete mortar in the subsequent step.

Fig. 4 shows one example of a practical installation designed by taking into consideration above described factors. More particularly, an elongated inclined trough 34 is installed beneath the lower end of the casing 10 and the receptacle 9 is formed like a funnel with its lower end 18b faced to a conveyor 11 so that certain amount ofthe sand particles adjusted their water quantity accumulates in the lower portion ofthe receptacle 9 so as to substantially seal the same. A discharge pipe 34a is provided between the lower end ofthe tough 34 and a funnel shaped water receiver 36 contained in a drain water tank 35 for accumulating the separated water in the water receiver 36. An inclined endless conveyor 33 with pick up pieces 33a is provided to discharge solid components accumulated in the bottom portion of the receiver 36 out of the water tank 18. Also a discharge pipe 32 having a suction port 23 is provided to discharge the water in the water tank 35 by a suitable pump, not shown, for using the water to prepare cement mortar or concrete. A water feed pipe 25 having a level detector 24 is provided for the water tank 35 so as to maintain the level of the water contained therein always at a constant level. If desired, the water feed pipe 25 may be opened in the trough 34 to clean the same or opened near the discharge end of a conveyor 30 utilized to load sand particles into the hopper 1 for adding water to the sand particles.

Although the purpose ofthe water separator of this invention is to adjust the quantity of the water deposited on the sand particles, that is the surface water, when the sand is substantially dry, i.e. contains only a small quantity of water, it is necessary to add water to the sand container in the hopper 1. As above described, in some case, the sand contains mud or clay which tends to adhere to the surface ofthe annular ring 6 especially when the water content ofthe sand is low, so that addition of water is effective. Thus, the added water removes the mud or clay deposited on the annular ring.

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Where the tendency of depositing mud or clay on the inner surface ofthe annular ring 6 is large a scraper 28 is mounted on the lower end of a shaft 27 rotated by a motor 4a at a relatively low speed, for 5 example less than 10 rpm. A layer of mud deposited on the annular ring 6 acts as a cushion layer so that the effect of adjusting the quantity of water by using an impactforce would be impaired. Moreover, the' adhesive layer ofthe deposited mud arrests the sand 10 particles. Where such adhesive mud layer is removed by the scraper 28, the efficiency of adjusting the water quantity can be improved.

A screw 29 may be mounted on the vertical shaft 27 to constantly feed the sand onto the rotating disc 15 2 from the hopper 1. Variation in the quantity of the sand supplied to the rotating disc 2 prevents uniform adjustment ofthe water content.

Details of modified water separator are shown in Figs. 5 to 8. As shown in Fig. 5, a vertical supply pipe 20 51a connected to the bottom of a hopper 51 is directed to the central portion of a rotating disc 52 and at the lower end ofthe supply pipe 51a are formed discharge openings 51 b on the opposite sides. As shown in Fig. 7, the rotating disc 52 is 25 provided with a plurality of radial vanes 57 for distributing and projecting sand particles supplied through the discharge openings 51 b. As shown in Figs. 6 and 8, the rotating disc 52 is contained in an inverted dish shaped rectangular impact frame 60 so 30 that the projected sand particles collide against the inner surface 60a ofthe impact frame 60. The lower end thereof surrounds the upper end of a receptacle 59 with gaps 59a therebetween, and water receiving troughs 58 are mounted near the upper ends ofthe 35 shorter sides ofthe receptacle to receive separate waterthrough gaps 59a. A bushing 54 adapted to support the rotating disc 52 is rotatably supported by a supporting cylinder 56 at the upper centre ofthe impact frame 60 through bearings 53 and pulley 55 is 40 secured to the upper end ofthe bushing 54 for rotating the rotating disc at a predetermined speed by an electric motor, not shown.

The modified embodiment shown in Figs. 5 to 8 operates as follows:

45 Thus, the sand particles supplied from the hopper 51 is discharged on the rotating disc 52 in the specified direction, i.e. about the middle ofthe longer sides of the impact frame 60 in case of example shown in Fig. 9 and the sand particles 50 projected by the rotating disc 52 are directed mainly to the shorter sides ofthe impact frame 60. The sand particles projected upon the longer sides will be guided to the shorter sides by an angle between the projection and the longer sides. In other words, 55 substantially all portions ofthe projected sand particles would collide upon the shorter sides where excessive water is removed by the impactforce, whereby sand particles with adjusted quantity of water would be collected in the receptacle. The 60 separated water flows down along the inner surface 60a ofthe impact frame 60 and then received by troughs 58. Mud or clay contained in the original sand is also collected in the troughs 58. With this modification, as substantially all projected sand 65 particles are caused to collide upon the shorter sides, the efficiency of water quantity adjustment can be provided.

Still another modification ofthe water separator and various modification of its parts are shown in 70 Figs. 9 to 14. In the modification shown in Figs. 9 to 11 an impact frame 60£> takes the form of an inverted frustum of a cone and is constructed such, that its impact surfaces can be exchanged. The sand particles from the hopper 51 are caused to collide upon 75 the inner surface ofthe impactframeto be removed excess water. Since the sand particles are abrasive, the inner surface ofthe impact frame 60£> wears rapidly. Accordingly, an impact plate 68 is divided into a plurality of sections and each section is 80 secured to the impact frame through a packing 68b by a fastener 68c as shown in Figs. 9 and 10. To exchange a section it is inclined by a handle 68a and then pulled out ofthe impact frame 60b through an opening 60c. About the lower skirt 60d a portion of 85 the impact frame 60£> is provided with an annular water tank 62. Cleaning water is supplied into the water tank 62 through an inlet port 62a to a level higherthan the upper edge ofthe skirt 60 d by h. The purpose ofthe cleaning water is to prevent stagna-90 tion of mud contained in the water. The water overflows through a discharge port 62b into a water receiving trough 58. Also the water flows along the inner surface of the skirt 62dtowards the water receiving trough 58.

95 When the water separator is used in the field, the sand particles tend to adhere to the inner surface of the receptacle 59. To prevent this tendency, a vibrator 61 is installed in the receptacle 59. The sand particles adhere especially to the upper portion of 100 the receptacle, so means for removing the deposited sand particles are provided for the upper portion as shown in Figs. 12,13, and 14.

In an example shown in Fig. 12, an air bag 67 is interposed between the side wall 59 a ofthe recepta-105 cle 59 and a hard rubber ring 66. By periodically varying the air pressure in the air bag 67 the sand particles deposited on the inner surface ofthe hard rubber ring 66 can be readily removed. In the example shown in Fig. 13, only the hard rubber ring 110 66 is secured to the upper edge receptacle 59. Even with this simple construction, the hard rubber ring 66 is caused to vibrate by the sand particles blasted thereon, thus peeling off the deposited sand particles. In the example shown in Fig. 14 a hard rubber 115 ring 66 a is secured to the upper portion 59a ofthe receptacle 59 with a suitable air gap 65 therebetween. With the construction shown in Fig. 14, the hard rubber ring 66a can vibrate more freely to more efficiently remove the deposited sand particles. 120 In the water separator described above, since the mud deposited on the skirt 60 and the sand particles deposited on the upper portion ofthe receptacle increase their volume with time, these deposited substances prevent smooth flow of water or sand 125 particles; it will be clearly noted that use of the means for removing deposited substances is advantageous. When a rotating disc provided with vanes is used, air flow is created along the wall surfaces which is more or less effective to prevent deposition, 130 but where the sand particles deposit, it will prevent

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smooth flow of air and grows rapidly.

Fig. 15 shows another example of the water separator with removes excessive water by an impact force without utilizing the centrifugal force 5 created by the rotating disc. In this modification, a fine aggregate, i.e. sand, is loaded into a hopper 1 by a conveyor 71 and then supplied to a horizontal rotor 77 provided with a plurality of radial vanes 79 by a metering device 76 which sequentially supplies the 10 sand of a definite quantity. The rotor 11 is rotated by an electric motor 74to apply a definite impactforce to the sand particle received by the rotor. In front of the rotor 77 are disposed first to third hoppers 84,85, and 86 to receive sand particles projected in the 15 foreward direction by the rotor 77. Each hopper is provided with a discharge damper 83 for discharging sand particles collected in the hopper.

More particularly, the first hopper 84 is used to receive water and mud deposited on the sand 20 particles, whereas the second and third hoppers 85 and 86 are used to receive sand particles with their surface water has been adjusted. The hopper 86 collects coarse sand particles. Generally speaking, the sand particles impacted by the rotor are pro-25 jected over different distances depending upon the mass ofthe sand particles. Water content adheres to the vanes and gathered at the tip ofthe vanes 79 by centrifugal force and then discharge into the hopper 84 in the form of drops. A cover 200 is provided to 30 cover hoppers 84,85, and 86 which are partitioned by adjustable partition plates 81.

As above described, with the water separator shown in Fig. 15, excess water is removed by an impactforce while the sand particles are classified 35 according to their particle size. Since the quantity of water remaining on the treated sand particles differs depending upon the particle size, this modified water separator is especially suitable for a fine aggregate containing particles of different size be-40 cause the sand particles are classified according to their size. Accordingly, the sand particles collected in each ofthe hoppers 85 and 86 have substantially the same particle size and the quantity of water remaining on the sand particles is also substantially 45 constant.

Still another embodiments of the water separators are illustrated in Figs. 16 and 17. In Fig. 16, the fine aggregate, i.e. sand, is caused to drop between a pair of parallel spaced-apart hard rubber rotors 75 50 which are rotated at a speed higher than the falling speed of the sand, and is then discharged downwardly to impinge upon an inclined impact plate 78 secured by a fastener 78c. Then, the water deposited on the surface ofthe sand particles is separated and 55 the sand particles are deflected to the left as shown by solid arrows to be taken out through a discharge port 73. The separated water and mud are collected in a trough 74. Cleaning water is supplied and discharged from a storage tank 62 through inlet and 60 outlet ports 62a and 62b in the same manner as in the embodiment shown in Fig. 11 to wash away mud accumulated on the rear side ofthe skirt 62 d. The sand particles may be projected in the horizontal direction or slightly downwardly in the same manner 65 as in Figs. 5 to 14. Furthermore, two or more pairs of the rotors 75 may be juxtaposed to increase the quantity ofthe sand to be treated.

In still another modification shown in Fig. 17, the sand particles dropping from the hopper are projected at a high speed against an inclined impact plate 78 secured by a fastener 78e by means of a pair of conveyors 72 running at a high speed, and cleaning water is supplied to a skirt 62d at a lower position than the impact plate 78 to prevent mud from adhering to the inner surface of the skirt. By the high speed belt conveyors 72 a large velocity energy is applied to the projected sand particles regardless ofthe quantity thereof. Where it is not desired to run the belt conveyors 72 at a high speed, the upper belt conveyor 72 is replaced by a rotating member 80 situated at the discharge end ofthe lower belt conveyor so as to impart the required velocity energy. Where the belt conveyors are run at a high speed, the sand particles tend to jump and splash, thereby decreasing the efficiency of imparting the velocity energy. With the construction shown in Fig. 18 it is possible to efficiency remove water without dropping the sand particles away from the conveyor. Where it is not desirable to project the sand particles in the horizontal direction against gravity, the sand particles may be projected downwardly in the same manner as in Fig. 16.

According to the embodiments described above, since substantially all sand particles imparted a high velocity energy are caused to collide upon the impact plate, the impact plate wears quickly so that it is necessary to frequently exchange the same. The modification shown in Fig. 19 is constructed to obviate this problem and comprises a pair of spaced belt conveyors 95 adapted to impart high velocity energy to the sand particles so that sand particles projected by the belt conveyors collide with each other in a space between the conveyors, thus sprinkling the water removed from the sand particles in the space. A motor driven blower 241 is used to exhaust air entraining the sprinkled water to the outside through a duct 212 which may contain a mist separator (not shown). With this construction, although all projected sand particles do not collide with each other, only a small amount ofthe projected sand particles collide upon an inverted funnel shaped impact plate 212, so that the wear thereof is small.

With the embodiment shown in Fig. 19, however, the impactforce is different for respective sand particles so that the quantity of the water remaining on the sand particles is not always constant. To eliminate this problem, an impact plate 234 shown by dot and dash lines may be positioned between the belt conveyors 235. Where sand particles containing mud are projected, the impact plate 94 is taken out through a window, not shown, and cleaned. The impact plate 234 may be a thick casting.

In any ofthe embodiments described above, substantially uniform impact force is imparted to the fine aggregate so as to remove excess water. So long as the impactforce is largerthan the adhering force ofthe water to the particles ofthe fine aggregate it is possible to remove surplus water. The removed water flows down along the impact

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plate while the particles ofthe fine aggregate are permitted to fall down or move outwardly.

The result of water separation effected by the water separator according to this invention is shown 5 in Fig. 20. As can be noted from the curves shown in Fig. 20, irrespective ofthe difference in the quantity ofthe surface water which differs dependent upon the particle size, so long as the quantity ofthe surface water exceeds a predetermined limit before 10 treatment, substantially constant quantity of water remains on the sand particles after the treatment. Even when the quantity ofthe initial water is less than the predetermined limit, a quantity of water proportional to the initial water quantity can be 15 removed. When the impulse force is increase by increasing the speed ofthe rotating disc the quantity ofthe water remaining afterthe treatment decreases, and vice versa, but the shape ofthe resulting curves resembles to that shown in Fig. 20. For this reason, 20 in order to make uniform the quantity of water remaining after the treatment, a quantity of water is added to the fine aggregate to adjust its initial water quantity to be higher than 15%, for example.

To have better understanding ofthe invention the 25 following Examples are given.

Example 1

In this example the apparatus shown in Fig. 1 was used which is provided with a rotating disc 2 having a diameter of 400 mm and driven by motor 4 at a 30 speed of 1100 rpm. Fine river sand containing 3.98% of water and having a'finess modulus (F.M.) of 1.28 mm, said F.M. determined according to the equation 6

F.M. = Z Pn/100, where Pn is weight percent of 35 n=1

aggregate remaining in a mesh of 0.15,0.3,0.6,1.2, 2.5 or 5.0 mm after meshing, the quantity of surface water varying from 4% to 25%, was supplied to the rotating disc 2 to cause the sand particles to collide 40 upon the impact plate 6. The rate of supply ofthe water containing sand to the hopper 1 was varied in a range of 50 to 160 kg/min and the water content of the sand conveyed by the conveyor 11 was measured to be 9.4-10.1 %, showing that the quantity of 45 the surface water is substantially constant.

Where the speed ofthe rotating disc 2 was increased to 5000 rpm the quantity of the surface water was measured to be 6.06-6.38%, which shows that the quantity ofthe surface water was substan-50 tially reduced from that when the rotating disc was rotated at a lower speed and the variation in the quantity ofthe surface water is much smaller. Example 2

With the same apparatus utilized in Example 1, 55 sand particles of medium size and containing 2.25% of water and having F.M. of 2.28 mm was treated in the same manner. In this example, however, water was added to the sand at the exit of the hopper 1 at a rate of 4l/min. When the rotating disc 2 was rotated 60 at a speed of 1100 rpm the water content ofthe treated sand was 4.7-5.3% showing that the quantity of the surface water has been decreased because the treated sand had a larger particle size. However, it was found that the range in which the quantity of the 65 surface water varies has been narrowed. In contrast.

when the speed ofthe rotating disc 2 was increased to 5,000 rpm the quantity ofthe surface water varied in a narrower range of 4.33 to 4.85%.

Example 3

Coarse sand produced from a different origin from that utilized in Example 1 and having a water content of 3.31% and F.M. of 2.96 mm was treated in the same manner as in Example 2. More particularly,

when the rotating disc 2 was rotated at a relatively low speed of 1100 rpm, the quantity ofthe surface water was 3.3-4.2% whereas at a higher rotating speed of 5000 rpm, the quantity ofthe surface water was 3.2 to 3.52%, showing a narrower range.

Example 4

In this example, the apparatus shown in Figs. 3 and 4 was used in which the rotating disc 2 having a diameter of 450 mm was rotated by motor 4 at a speed of 1250 rpm. Medium size river sand having a water content of 2.25% and F.M. of 3.27% was caused to collide against the impact plate 6. Water-containing sand was fed into the hopper 1 at a rate of 25 m3/hour. 5-40 l/min of water was sprinkled onto the sand while it was being conveyed by conveyor 30. The treated sand collected in the bottom portion ofthe receptacle 9 was conveyed by the conveyor 11. The conveyed sand was sampled at each minute to measure the water content ofthe treated sand. The water content measured was in a range of 8.79-8.93% and it was found that the quantity ofthe surface water was substantially constant, i.e. from 6.54 to 6.58%. The quantity ofthe recovered sand after the treatment was 24.1 m3/hour, showing a high yield of 96.2%. Not recovered quantity consisted essentially of mud.

When the speed ofthe rotating disc 2 was increased to 1500 rpm the water content ofthe treated sand was 6.92-7.04% (the quantity ofthe surface water is 4.66-4.77%). At a higher speed of 1750 rpm, the water content of the treated sand was 5.79-5.88% (the quantity of the su rface water was 3.53-3.62%). Thus, in each case the quantity of the surface water was reduced and is substantially constant. The quantity ofthe treated and recovered sand was 24.28 mS3/hour for 1500 rpm, and 24.52 m3/hour for 1750 rpm.

Example 5

The same apparatus utilized in Example 4 was used to treat medium size sea sand having a water content of 2.46%, a salt content of 0.33% of F.M. of 2.62%. In this example, 30 l/min of water was added to the sand while it was conveyed by the conveyor.

In this Example, when the rotating disc was rotated at a lower speed, the water content ofthe treated sand was 8.56-8.71% (the quantity of the surface water was 6.40-6.55%. Even with the same rotation speed of the disc, since the sand is coarse, its quantity of surface water has been decreased. Although the treated sand still contains 0.03% of salt, it can be used for preparing green mortar or green concrete because ofthe formation ofthe cement shells, and the quantity ofthe recovered sand was 23.8 m3/hour.

When the rotating disc 2 was rotated at a speed of 1500 rpm the water content of the treated sand was 6.76-6.83% (the quantity of the surface water was 4.30-4.37%) whereas when the speed ofthe rotating disc

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Claims

? GB 2 m 659 A 7 was increased to 1750 rpm, the water content ofthe treated sand was 5.51-5.58% (the quantity ofthe surface water was 3.05-3.12, which shows that the variation in the water quantity is also small. The salt 5 contents were 0.028% and 0.027% for 1500 rpm and 1750 rpm respectively and such salt-containing sand could be used to prepare a concrete compound. To remove salt it is usual to use clean water in a quantity at least equal to that of sea sand, so that to 10 remove salt from 25 m3 of sea sand it is necessary to use 25-80 m3 of clean water. In contrast, according to this example the quantity of water added to the sea sand is only 30 l/min, or 1.8 m3/hour. When salt is removed by sprinkling water onto sea 15 sand, the salt is not removed uniformly. For example, even though the average quantity ofthe remaining water is 0.03%, it varies between 0.002 and 0.150%, meaning that a considerable quantity of washed water contained more than 0.04% ofthe 20 remaining salt, which is the permissible upper limit. According to this example, when water is added to the sea sand being conveyed by the conveyor at a rate of only 30 l/min, since the separation of water is efficiently performed by the impact force, the quanti-25 ty ofthe remaining salt is only 0.007-0.038%. Example 6 Fine particles of a slag pulverized by water and having F.M. of 2.53 mm and containing 2.90% of water was treated in the same manner as in Example 30 4. More particularly, when water is removed at the rotating speed of 1250 rpm ofthe disc 2, the water content ofthe slag particles was 8.99-9.27% (the quantity ofthe surface water was 6.09-6.37%) 35 whereas the speed of 1750 rpm, the water content was decreased to 6.19-6.28% (the quantity ofthe surface water was 4.29-4.38%) and the quantity recovered sand was 24.0 m3,24.3 m3, and 24.51 m3 at the speeds of 1250,1500, and 1750 rpm respec-40 tively. Example 7 In this example, the apparatus shown in Figs. 5-8 was used. Coal dust having a particle size of 0.15-5 mm and containing 3-15% of surface water was 45 treated by the apparatus. The feed speed was selected in a range of from 80 to 200 kg/min. The rotating member 52 was provided with vanes having a length of 250 mm between the axis and the outer end and the rotating member was rotated at a 50 speed of 1500 rpm to remove water from the coal dust. After treatment, the coal dust contained 4.2-4.3% ofthe surface water showing uniform water removal. Mud on the particles ofthe coal dust was also efficiency separated. 55 Example 8 In this example, the apparatus shown in Figs. 9, 10, and 11 was used to remove water from blast furnace slag containing 20.5-57.5% of surface water. The rotating member 52 has a radius of 300 mm 60 and rotated at a speed of 2000 rpm. The treated slag contained 12-15% ofthe surface water. The particle size ofthe slag was largerthan 0.1 m which can be classified. Example 9 65 The apparatus shown in Figs. 5-8 was used, and in this example mineral particles having a water content of 28-46% and a grain size of less than 3 mm was preheated to about 80°C and then supplied to the hopper 1. 70 The rotating member 52 was provided with blades having a length of 250 mm between the axis and the ends ofthe blades. The rotating body was rotated at a speed of 1850 rpm, and the impact plate 60a was heated to about 60°C. After the treatment, the 75 quantity of oil remaining on the mineral particles was 4.8-5.3%, showing substantially uniform removal of oil. According to a prior art method of removing oil contained in mineral particles, the oil was removed 80 by evaporation. To this end it has been necessary to heat the particles ata high temperature of 500°Cfora considerable period while agitating. Furthermore it is necessary to recover evaporated oil by condensation, which requires an expensive equipment. In 85 contrast, the apparatus of this invention is simple in construction, consuming less operating energy. CLAIMS

1. A method of adjusting the quantity of a liquid adhering to the surfaces of fine particles, comprising

90 applying to the particles an impulsive force larger than the adhesive force ofthe liquid, thereby removing at least part ofthe liquid.

2. A method as claimed in claim 1, wherein the said force is due to kinetic energy.

95

3. A method as claimed in claim 2, wherein the kinetic energy is imparted by centrifugal force of a gas flow or both.

4. A method as claimed in claim 1, wherein the said force is applied to the particles by a rotating

100 member.

5. A method as claimed in claim 1, including the further steps of applying liquid to the particles in an amount largerthan the quantity of water remaining on the particles afterthe application ofthe said force,

105 and then applying to the particles a substantially uniform impulse force.

6. A method as claimed in claim 1, wherein the particles have different quantities ofthe liquid thereon.

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7. A method as claimed in claim 1, wherein the particles are of equal grain size.

8. A method as claimed in claim 1, wherein the said force is applied by centrifugal force in a closed chamber.

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9. A method as claimed in claim 1, wherein the particles are contaminated with an inpurity, the method comprising the §teps of adding liquid to the fine particles and then applying the said force to simultaneously remove impurity and adjust the

120 quantity of liquid.

10. Apparatus for separating liquid from fine particles comprising liquid separating means for applying an impulsive force to the particles so as to remove liquid from the particles and means for

125 successively supplying the particles to the liquid separating means.

11. Apparatus as claimed in claim 10, which further comprises means for supplying liquid to the particles before they are supplied to the liquid

130 separating means.

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12. Apparatus as claimed in claim 10, wherein the liquid separating means comprises a rotatable disc and an impact plate against which the particles are projected by centrifugal force created by the

5 rotating disc.

13. Apparatus as claimed in claim 12, wherein the disc is provided with a plurality of radial vanes and the particles are supplied to a central portion of the disc.

10

14. Apparatus as claimed in claim 10, wherein the impulsive force is applied by pressurized gas.

15. Apparatus as claimed in claim 10, wherein the impulsive force is applied by a conveyor belt running at a high speed.

15

16. Apparatus as claimed in claim 12, which further comprises means for dividing the particles from the liquid separated from the particles as a result of collision against the impact plate.

17. Apparatus as claimed in claim 16, wherein

20 the said dividing means is provided on an upper edge of a container of particles from which liquid has been removed.

18. Apparatus as claimed in claim 6, substantially as described with reference to, and as shown in, Figure 1, Figure 2, Figure 3, Figure 4, Figures 5 to 8, 10 Figures9to 11, Figure 15, Figure 16, Figure 17,

Figure 18, or Figure 19 ofthe accompanying draw-ings.

Printed for Her Majesty's Stationery Office by The Tweeddale Press Ltd., Berwick-upon-Tweed, 1983.

Published at the Patent Office, 25 Southampton Buildings, London, WC2A1AY, from which copies may be obtained.

18. Apparatus as claimed in claim 12, wherein the impact plate is removably mounted on an

25 inverted dish shaped member whereby water removed from the particles as a result of collision against the impact plate flows down along an inner surface ofthe member.

19. Apparatus as claimed in claim 12, including a

30 pipe for continuously supplying the particles to a central portion ofthe disc and means for adding liquid to the particles at the exit end ofthe pipe.

20. Apparatus as claimed in claim 18, which further comprises a receiver of treated particles, an

35 upper edge of the receiver being spaced from a lower edge ofthe inverted dish shaped member.

21. Apparatus as claimed in claim 12, wherein the disc is contained in a casing having a rectangular cross-sectional configuration and inner surfaces of

40 the casing are inclined downwardly in the path of particles projected by the rotating disc.

22. Apparatus as cfaimed in claim 12, which further comprises means for supplying cleaning liquid to the impact plate.

45 23. Apparatus as claimed in claim 12, which further comprises a receptacle for receiving particles projected upon the impact plate, and means for removing particles adhering to an upper portion of the receptacle.

50 24. Apparatus as claimed in claim 23, wherein the removing means comprises an elastic tube.

25. Apparatus as claimed in claim 24, which further comprises means for inflating the elastic tube.

55 26. Apparatus as claimed in claim 10, wherein the liquid separating means comprises a wheel rotatable about a horizontal axis and having a plurality of radial vanes, means for supplying the fine particles to a space between adjacent vanes,

60 means for rotating the wheel at a speed sufficient to remove liquid from the particles, means for discharging the particles from the wheel substantially in a horizontal direction and a plurality of particle receivers juxtaposed in the horizontal direction to

65 classify the particles according to their size.

New claims or amendment to claims filed on 4th Nov 1982.

New or amended claims:-

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1. A method of separating a liquid adhering to the surface of fine particles therefrom, comprising applying to the particles an impulsive force larger than the adhesive force ofthe liquid by causing the

75 particles to collide with a body, thereby removing at least part ofthe liquid, the impulsive force being generated with the aid of a rotating member.

2. A method as claimed in claim 1, including the step of applying liquid to the particles before the

80 impulsive force is applied to the particles, thereby establishing that the particles have the liquid in an amount largerthan the quantity ofthe liquid remaining on the particles after collision.

3. A method as claimed in claim 1 or 2, wherein

85 the fine particles are particles of a fine aggregate and the liquid is water.

4. A method as claimed in any of claims 1 to 3, wherein the particles are projected by the rotating member and the projected particles collide with the

90 body.

5. A method as claimed in any of claims 1 to 3, wherein the body is constituted by the rotating member.

6. Apparatus for separating a liquid adhering to

95 the surface of fine particles therefrom, comprising means for applying to the particles an impulsive force largerthan the adhesive force ofthe liquid by causing the particles to collide with a body, and means for supplying the particles to the force-ap-

100 plying means, the force-applying means comprising a rotatable member.

7. Apparatus as claimed in claim 6, further comprising means for applying liquid to the particles before the impulsive force is applied to them.

105 8. Apparatus as claimed in claim 6 or 7, wherein the particles are projected by the rotatable member and the projected particles collide with the body.

9. Apparatus as claimed in claim 8, wherein the rotatable member comprises a disc rotatable about a

110 vertical axis for projecting the particles against the body by centrifugal force.

10. Apparatus as claimed in claim 9, wherein the disc is provided with a plurality of radial vanes, and the particles are supplied to a central portion ofthe

115 disc.

11. Apparatus as claimed in claim 8, wherein the rotatable member comprises a pair of rotors having mutually parallel horizontal axes, the particles being supplied between the rotors.

120 12. Apparatus as claimed in claim 11, wherein the rotors are made of hard rubber.

13. Apparatus as claimed in any of claims 8 to 12, wherein the body for collision with the particles is mounted detachably.

125 14. Apparatus as claimed in any of claims 8 to 13, wherein the body is provided with means for removing the liquid deposited thereon.

15. Apparatus as claimed in claim 9 or 10, wherein the disc is installed within a casing provided

130 inside with a collision wall, and including means for

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separating the particles from the liquid flowing down along the inner surface ofthe casing.

16. Apparatus as claimed in claim 6 or 7, wherein the body is constituted by the rotatable member. 5 17. A method as claimed in claim 1, substantially as described in any of the Examples given.