GB2088233A

GB2088233A - Method and Apparatus for Draining of Granulated Blast- furnace Slag

Info

Publication number: GB2088233A
Application number: GB8124486A
Authority: GB
Original assignee: Ajo Stahlbau GmbH and Co KG
Current assignee: Ajo Stahlbau GmbH and Co KG
Priority date: 1977-11-03
Filing date: 1978-11-01
Publication date: 1982-06-09
Also published as: AU4127378A; SE443357B; AT363969B; SE8400627L; PL124161B1; SE7811366L; NL7810971A; PL210680A1; SE8400627D0; AU532442B2; IT7829413A0; FR2407729B1; BR7807231A; LU80440A1; GB2088233B; GB2007519A; IT1100451B; GB2007519B; ATA785078A; FR2407729A1

Abstract

A mixture of granulated blast furnace slag and water, formed by the injection of water into liquid slag, is fed to vessel (104) and the granulated slag is lifted and drained by a plurality of perforated bowls (106) positioned on a scoop wheel (101) and dropped on to a conveyor (108). Water, contaminated by fine solids, overflows from vessel (104) and is fed to settling vessel (103) which has a possibly tangential inlet to central chamber (121), radial and peripheral overflow channels leading to outlet (130), from which water is recycled to the granulation process, and a solids- collecting sump (118). Fine solids plus some water are pumped from sump (118) to nozzles (133) so that the solids are retained by the coarser slag particles in bowls (106). When the wheel (101) is not running, the solids are recycled to chamber (121). Settling tank (130) may replace lines (132, 136). <IMAGE>

Description

1 GB 2 088 233 A 1.

SPECIFICATION

Method and Apparatus for the Draining of Granular Material, Particularly Granulated Blast-furnace Slag This invention relates to a method and an 70 apparatus for draining liquid from loose granular material. In the draining of natural sand or shingle, the water/sand mixture is supplied by a suction dredge from a dredge pool to a scoop wheel device via pipe lines. The scoop wheel lifts the 75 sand and/or shingle with the water from a bucket into perforated bowls, and after about half a revolution, transfers it via a funnel to a continuous conveyor, e.g. a conveyor belt, from which it then, by way of example, arrives at a loading silo. The 80 water flowing over the scoop wheel bucket is returned to the dredge pool. This redirected water still contains sand which is not important in the obtaining of natural sand or shingle since the embankment of sand or shingle which forms in 85 the dredge pool from the redirected water can later be removed again.

In the draining of granular materials which are formed by the action of water as, for example, in the draining of blast-furnace slag which is formed 90 by the injection of water into the flow of hot, liquid slag, the water must be conveyed in closed circulation in order to submit it to reuse. For this purpose, drainage silo systems are known in which the granulated slag/water mixture is supplied to several drainage silos in rotation via overhead pipe lines, which system requires suitable pumping apparatus. The cost is therefore correspondingly high. The use of scoop wheel washing in the production of blast-furnace slag 100 creates difficulties, since the drawn-off water contains too large a proportion of granular material. The granular material could be collected in a suitably large and deep settling tank, but this would then require too frequent emptying of the 105 settling tank.

According to a first aspect of the present invention, there is provided a method of draining liquid from loose granular material comprising the steps of:

collecting a liquid/granular material mixture in perforated bowls mounted on a rotatable wheel so as to drain the liquid from the granular material, the liquid collecting in a trough below the rotatable wheel; transferring the drained granular material from the perforated bowls onto a conveyor; allowing excess liquid in the trough to overflow into a channel; and processing the overflowing liquid so as to 120 concentrate suspended particles in a concentrate portion of the liquid, and to obtain the remainder of the liquid in clarified form.

The drained granular material may be transferred onto the conveyor via a funnel. 125 Preferably, the concentrate portion of the liquid is fed to the perforated bowls where the particles are removed by means of the granular material in the bowls acting as a filter.

The mixture may comprise a mixture of water and blast furnace slag which has been granulated by the injection of water into the liquid slag. In this case the clarified liquid which is obtained in accordance with the invention may be re-used by injecting it into liquid slag to granulate the slag and form a liquid/granular slag mixture.

According to a second aspect of the present invention there is provided an apparatus for draining liquid from loose granular material, which apparatus comprises:

a rotatable wheel having mounted thereon a plurality of perforated bowls for receiving a liquid/granular material mixture and for draining the liquid from the granular material; a conveyor for receiving drained granular material; a trough located below the rotatable wheel for collecting the liquid draining from the granular material; a channel arranged alongside the trough for receiving excess liquid overflowing from the trough; and a thickener for receiving and concentrating the liquid overflowing into the channel, the upper part of the thickener being provided with a flow stabilising and solids separating chamber for producing liquid which is relatively free of solids and the lower part of the thickener being in the form of a collecting chamber for the liquid which is relatively concentrated in solids, the lower part of said collecting chamber being provided with an outlet for a concentrated liquid/solids mixture.

The thickener preferably comprises an inner container in communication with an outer container, the inner container being provided with an inlet for liquid drained from the granular material and the outer container being provided with a circular overflow channel, the collecting chamber being in the form of a funnel.

Radial overflow channels may extend between the inner container and the circular overflow channel, the radial overflow channels being connected to the circular overflow channel.

The liquid draining from the granular material may be fed into the thickener via the trough and the channel by means of a tangential inlet pipe.

The apparatus may include a feed pump for pumping concentrated liquid/solids from the outlet of the collecting chamber to a feeding device disposed above the perforated bowls which contain liquid/granular material mixture. The feeding device is preferably in the form of nozzles.

The apparatus may include a pipe provided with a shut-off device connecting the outlet of the collecting chamber with the inlet of the thickener.

As an alternative to the pump the apparatus may include a settling tank connecting to the outlet of the collecting chamber.

The method and apparatus according to the invention make possible an effective draining of loose granular material at the same time as the obtaining of good quality water which can be reused for example injected into liquid slag to 2j, GB 2 088 233 A 2 - granulate the same. The apparatus, at least in some embodiments thereof, is characterised by reduced expenditure in construction and consequently lower production costs, greater operating reliability and also the need for much less space. For a better understanding of the present invention and to show more clearly how it may be carried into effect, reference will now be made, by way of example, to the accompanying drawings in 75 which:Figure 1 is a diagrammatic representation of an installation according to the invention for the draining of blast-furnace slag; and 15 Figure 2 is a top view of a thickener or concentrator of the drainage installation shown in Figure 1. The installation of Figures 1 and 2 is for the draining of blast-furnace slag and comprises a 20 scoop wheel 10 1 and a clarifying device 102 including a thickener or concentrator 103. The scoop wheel 101 rotates in a trough 104 into which the slag sand/water mixture flows via a feed pipe 105, the slag sand/water mixture being produced in a granulating device (not illustrated) by injecting pressure water into the liquid slag arriving from a blast-furnace. The scoop wheel 101 removes the slag sand/water mixture from the trough 104 with perforated bowls 106 and, after about half a revolution, conveys the sand into the funnel 107. The drained water flows back into the trough 104 from the perforated bowls 106. The sand fails from the funnel 107 onto a conveyor belt 108 which then carries the sand away.

Each of the two longitudinal sides of the scoop wheel trough 104 is provided with an overflow channel 109 having an inclined base 110 into which the water, which is contaminated by solid substances overflows. A feed pump 111, to which a pump receiver 11 21s connected in series, drains off the mixture of water and contaminating solid substance through an outlet 113 arranged at the lowest point of the channel base 110 and through a discharge pipe 114 and pumps the mixture through a connecting pipe 115 into the thickener 103. The mixture of water and contaminating solid substance can also be conveyed from the overflow channels 109 of the scoop wheel 10 1 into the thickener 103 by a connecting pipe of a sloping design instead of by the feed pump 111.

The thickener 103 is provided with a cylindrical outer container 116 with a circular overflow channel 117 and a collecting chamber in the form of a funnel 118 disposed at its lower end, the funnel being connected to a feed pump 120 via an outlet 11 8a and an offtake tube 119. The thickener 103 is also provided with an inner container 121 with a feed pipe 122 for the water/solid substance mixture pumped out from the overflow channels 109 of the scoop wheel 101. Thus, the inner container functions as a surge tank. Overflow channels 125 running in a radial direction are arranged between the inner container 121 apd the circular overflow channel 117 of the thickener 103. The radial overflow channels 125 are connected to the overflow channe1117.

The contaminated water i.e. the water/solid substance mixture drained off from the overflow channels 109 of the scoop wheel 10 1 by the feed pump 111 enters the inner container 121 via the feed pipe 122. Should a tangential feed pipe be chosen then the contaminated water flows in an initial spiral flow through the upper part of the inner container 121, the spiral flow being stabilized up to the lower end 123 of the inner container. The water leaving the inner container 121 at the lower end 123 rises in a laminar flow in the outer container 116 and flows via the radial channels 125 which, with their overflow rims 127, 128, receive water from the entire surface of the thickener 103, and via the circular overflow channel 117 with its overflow rim 129 through a discharge funnel 130 and an offtake tube 131 into a collecting tank not illustrated, to be re-used for injecting into liquid slag. The speed at which the water rises in the outer container 116 of the thickener 103 can be adapted to the sinking speed of the solid substances so that a minimalamount of micro-particles remains in the purified water which flows out of the thickener 103. The proportion of micro-particles in the purified water which is removed from the thickener 103 can be established by measuring the throughfiow cross- section between the outer container 116 and the inner container 12 1.

The feed pump 120 pumps the concentrated water/solid substance mixture through a connecting pipe 132 into a feeding device constructed, for example, from nozzles 133, which feeding device is disposed above the perforated bowls 106, which emerge from the water and are filled with slag sand/water mixture, of the rotary scoop wheel 10 1 with the direction of rotation indicated by arrow a. The slag sand conveyed in the perforated bowls 106 of the scoop wheel 101 forms a filter 134 for the concentrated water/solid substance mixture injected through the nozzles 133, which mixture separates off the solid substances.

When the scoop wheel 10 1 is at a standstill, the connecting pipe 132 is closed by a shut-off device 137 and the pump 120 conveys the concentrated water/solid substance mixture settling in the collecting funnel 118 of the thickener 103 into the inner container 121 of the thickener through a by-pass pipe 136 which is closed by a shut-off device 135 when the scoop wheel is in operation. This method ensures that not too much solid substance collects in the funnel 118 and that the concentrated mixture remains conveyable.

The delivery of the pump 120-amounts to a fraction of the inflow into the thickener 103, so that the quantity of concentrated water/solid substance mixture reaching the feeder nozzles 133 via the scoop wheel 10 1 can be regulated by altering the rotational speed of the pump 120.

In a modified embodiment of the drainage z 3 GB 2 088 233 A 3 device according to Figures 1 and 2 the following elements are omitted: the offtake tube 119 of the funnel 118 of the thickener 103, the feed pump and the connecting pipe 132 to the nozzles 133 via the scoop wheel 10 1, and the by-pass pipe 136 branching off from the connecting pipe 132 into the inner container 121 of the thickener 103. In this modified embodiment the outflow 11 8a of the funnel 118 of the thickener 103 is connected to a settling tank 139 via a connecting pipe 138.

This application is divided out of patent application No. 42742/78 which discloses and claims a method of draining liquid from loose granular material comprising the steps of:

collecting a liquid/granular material mixture in perforated bowls mounted on a rotatable wheel so as to drain the liquid from the granular material, the liquid collecting in a trough below the rotatable wheel; transferring the drained granular material from the perforated bowls onto a conveyor; allowing excess liquid in the trough to overflow into a channel; and filtering the overflowing liquid through a perforated base of the channel so as to clarify the liquid, floating and suspended particles forming a filter layer on the perforated base.

That application also discloses and claims an apparatus for draining liquid from loose granular material, which apparatus comprises:

a rotatable wheel having mounted thereon a plurality of perforated bowls for receiving a liquid/granular material mixture and for draining the liquid from the granular material; a conveyor for receiving drained granular 100 material; a trough located below the rotatable wheel for collecting the liquid draining from the granular material; a channel arranged alongside the trough for receiving excess liquid overflowing from the trough, the channel being provided with a perforated base for collecting floating and suspended particles; and a vertically adjustable scraper device for maintaining the layer of particles on the perforated base at a predetermined thickness.

Claims

Claims

1. A method of draining liquid from loose 115 granular material comprising the steps of:

collecting a liquid/granular material mixture in perforated bowls mounted on a rotatable wheel so as to drain the liquid from the granular material, the liquid collecting in a trough below the rotatable wheel; transferring the drained granular material from the perforated bowls onto a conveyor; allowing excess liquid in the trough to overflow into a channel; and processing the overflowing liquid so as to concentrate suspended particles in a concentrate portion of the liquid, and to obtain the remainder of the liquid in clarified form.

2. A method according to Claim 1, wherein the drained granular material is transferred onto the conveyor via a funnel.

3. A method according to Claim 1 or 2, wherein the concentrate portion of the liquid is fed to the perforated bowls wherein the particles are removed by means of the granular material in the bowls acting as a filter.

4. A method according to Claim 1, 2 or 3, wherein the mixture comprises a mixture of water and blast furnace slag which has been granulated by the injection of water into the liquid slag.

5. A method according to Claim 4 wherein the clarified liquid which is obtained is used for injection into the liquid slag to granulate the same and form a liquid/granular slag mixture.

6. A method of draining liquid from loose granular material substantially as hereinbefore described with reference to the accompanying drawings.

7. An apparatus for draining liquid from loose granularmaterial, which apparatus comprises:

a rotatable wheel having mounted thereon a plurality of perforated bowls for receiving a liquid/granular material mixture and for draining the liquid from the granular material; a conveyor for receiving drained granular material; a trough located below the rotatable wheel for collecting the liquid draining from the granular material; a channel arranged alongside the trough for receiving excess liquid overflowing from the trough; and a thickener for receiving and concentrating the liquid overflowing into the channel, the upper part of the thickener being provided with a flow stabilising and solids separating chamber for producing liquid which is relatively free of solids and the lower part of the thickener being in the form of a collecting chamber for the liquid which is relatively concentrated in solids, the lower part of said collecting chamber being provided with an outlet for a concentrated liquid/solids mixture.

8. An apparatus as claimed in Claim 7, wherein the thickener comprises an inner container in communication with an outer container, the inner container being provided with an inlet for liquid from the overflow channel and the outer container being provided with a circular overflow channel, the collecting chamber being in the form of a funnel.

9. An apparatus as claimed in Claim 8 and including radial overflow channels extending between the inner container and the circular overflow channel, the radial overflow channels being connected to the circular overflow channel.

10. An apparatus as claimed in Claim 7, 8 or 9, wherein the liquid overflowing from the trough into the channel is fed into the thickener by means of a tangential inlet pipe.

11. An apparatus as claimed in any one of Claims 7 to 10 and including a feed pump for pumping concentrated liquid/solids from the outlet of the collecting chamber to a feeding 4 GB 2 088 233 A 4 device disposed above the perforated bowls which contain liquid/granular material mixture. 12. An apparatus as claimed in Claim 11, wherein the feeding device is in the form of nozzles. 13. An apparatus as claimed in any one of Claims 7 to 12 and including a pipe provided with a shut-off device connecting the outlet of the collecting chamber with the inlet of the thickener. 10 14. An apparatus as claimed in any one of Claims 7 to 10 and including a settling tank connected to the outlet of the collecting chamber. 15. An apparatus as claimed in any one of Claims 7 to 14 and including an overflow channel arranged along opposite longitudinal sides of the trough.

16. An apparatus for draining liquid from loose granular material substantially as hereinbefore 60 described with reference to, and as shown in, the accompanying drawings.

New Claims or Amendments to Claims Filed on 25/11/81 Superseded Claims 1, 7, 8, 10,11, 15 New or Amended Claims:- 1, 7, 8, 10, 11, 15 1. A method of draining liquid from loose granular material comprising the steps of removing a liquid/granular material mixture from a trough below a rotating wheel by means of perforated bowls mounted on the rotating wheel so as to drain liquid from the granular material, the liquid collecting in the trough below the rotating wheel; transferring the drained granular material from the perforated bowls onto a conveyor; allowing excess liquid in the trough to - overflow into a channel; and processing the overflowing liquid so as to concentrate suspended particles in a concentrate portion of the liquid, and to obtain the remainder of the liquid in clarified form.

7. An apparatus for draining liquid from loose granular material, which apparatus comprises a 85 rotatable wheel and a trough located below the rotatable wheel, the rotatable wheel having mounted thereon a plurality of perforated bowls for removing a liquid/granular material mixture from the trough and for draining liquid from the granular material so that the liquid is collected by the trough; a conveyor for receiving drained granular material from the perforated bowls; a channel alongside the trough for receiving excess liquid overflowing from the trough; and a thickener for receiving and concentrating the liquid overflowing into the channel, the upper part of the thickener being provided with a flow stabilising and solids separating chamber for producing liquid which is relatively free of solids and the lower part of the thickener being in the form of a collecting chamber for the liquid which is relatively concentrated in solids, the lower part of said collecting chamber being provided with an outlet for a concentrated liquid/solids mixture.

8. An apparatus as claimed in Claim 7, wherein the thickener comprises an inner container in communication with an outer container, the inner container being provided with an inlet for liquid from the channel alongside the trough and the outer container being provided with a circular overflow channel, the collecting chamber being in the form of a funnel.

10. An apparatus as claimed in Claim 7, 8 or 9 and including a tangential inlet pipe for feeding the liquid overflowing from the trough into the channel alongside the trough into the thickener.

11. An apparatus as claimed in any one of Claims 7 to 10 and including a feed pump for pumping concentrated liquid/solids from the outlet of the collecting chamber to a feeding device disposed above the perforated bowls which in use contain liquid/granular material mixture.

15. An apparatus as claimed in any one of Claims 7 to 14 and including a second channel alongside the trough for receiving excess liquid overflowing from the trough, said channels alongside the trough being arranged alongside opposite longitudinal sides of the trough.

Printed for Her Majesty's Stationery Office by the Courier Press, Leamington Spa, 1982. Published by the Patent Office, 25 Southampton Buildings, London, WC2A 1 AY, from which copies may be obtained.

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