WO1999061126A1

WO1999061126A1 - Extraction apparatus

Info

Publication number: WO1999061126A1
Application number: PCT/GB1999/001439
Authority: WO
Inventors: Christopher John Broan
Original assignee: British Nuclear Fuels Plc
Priority date: 1998-05-22
Filing date: 1999-05-07
Publication date: 1999-12-02
Also published as: GB9810947D0; AU3837199A

Abstract

A baffle and electrode arrangement for an electrostatic pseudo liquid membrane cell for the extraction of a solute from an aqueous feed solution into an aqueous stripping solution via a non-aqueous carrier liquid is described, the baffle and electrode arrangement being such that an electrostatic field produced by the electrodes is reduced or removed at least in a region or regions of the cell where bulk flow of a carrier liquid between feed and stripping sides of the cell are at a maximum.

Description

EXTRACTION APPARATUS

The present invention relates to improvements to the so- called "electrostatic pseudo liquid membrane" (ESPLIM) method of separation of metal ions from aqueous solutions.

Chinese patent application number CN 86101730A describes a separation technique which enables the purification of aqueous solutions and concentration of solutes in aqueous solutions .

The technique includes the steps of passing droplets of an aqueous feed solution which it is desired to purify and/or from which it is desired to extract metal ions for example, under the influence of gravity, through a first region of a non-polar carrier liquid in which is dissolved a chemical having high affinity for the metal ion or ions to be removed whilst simultaneously subjecting the droplets to a high voltage electrostatic field so as to break up the droplets into a multiplicity of much smaller droplets in order to increase their surface area to volume ratio. The metal ions are complexed by the dissolved chemical into the carrier liquid and are driven, principally by the concentration gradient so formed, to a second region in the non-polar carrier liquid through which is passing under the influence of gravity a stream of droplets of an aqueous "stripping" solution which has a chemically higher affinity for the metal ion than the complexing chemical in the carrier liquid. The stripping solution droplets are also simultaneously subjected to a high voltage electrostatic field so as to break them up into a multiplicity of much smaller droplets and thus to increase their surface area to volume ratio. The metal ions are thus concentrated into the stripping solution and the aqueous feed solution is largely purified of the metal ions. As the very small droplets of the purified feed solution and the stripping solution, the former now having a lower concentration of the metal ions and the latter now having a high concentration of the required metal ions, pass out of the high voltage electrostatic field, they coalesce and fall under gravity into mutually separated first and second collecting vessels, respectively, and from which they can be removed.

The first and second regions of the carrier liquid are separated by a barrier or baffle which is intended to allow substantially uninterrupted flow and passage of the carrier liquid to and from the first and second regions but, is also intended to physically impede or prevent the passage of the aqueous feed solution from the first region into the second region and, the passage of the stripping solution from the second region to the first region.

In the above mentioned Chinese patent publication and all other ESPLIM related publications which we have seen, the baffle has been depicted as consisting of a vertical series of a plurality of inverted Vee-shaped baffle elements of symmetrical form as shown in Figure 6 where the side lengths LA and LB are equal; and, the angles φA and φB of each side LA and LB about a vertical axis are also equal. Furthermore, baffle elements in ESPLI related publications have always been shown as being of the same configuration throughout the height of the baffle.

According to a first aspect of the present invention there is provided a baffle and electrode arrangement for an electrostatic pseudo liquid membrane cell for the extraction of a solute from an aqueous feed solution, the baffle and electrode arrangement being such that an electrostatic field produced by the electrodes is reduced or removed at least in a region or regions of the cell where bulk flow of a carrier liquid between feed and stripping sides of the cell are at a maximum.

A problem which we have discovered is that contrary to the flow direction of the carrier liquid being governed by the concentration gradient therein of the species being extracted as previously believed, the flow of the organic carrier liquid is more strongly influenced by the physical flows of the aqueous phases passing therethrough. Furthermore, since the flow rate of the aqueous feed solution is usually far greater than that of the stripping solution, the flow pattern of the organic carrier phase within the cell is dominated by the flow of the feed solution and a relatively pronounced circular flow pattern is established in the carrier liquid. As may be seen in Figure 2, where the feed cell is on the left and the stripping cell is on the right hand side of the diagram, a generally anticlockwise flow pattern is generated with maximum transverse bulk flow between the feed and stripping sides at the lower and top ends of the feed and stripping sides, respectively.

It is the high intensity electrostatic fields produced by the electrodes in the feed and stripping sides which cause break-up of the feed and stripping streams into very small droplets which make them susceptible to being entrained and carried across the baffle region. In all prior art ESPLIM cells the electrostatic field has extended virtually to the top and bottom extremities of the vertical baffle arrangement which is where transverse bulk flow between the feed and strip sides is at a maximum. Thus, by reducing or removing the electrostatic field in these regions of maximum transverse flow, the droplets begin to become larger, by coalescence for example, and consequently become less susceptible to entrainment and being carried across the baffle region.

The desired effect may be achieved by offsetting the electrodes relative to each other whereby they do not extend so far in a downwardly direction in the feed side and do not extend so far in an upwardly direction on the stripping side.

Alternatively, the electrodes may be shortened in both the feed and stripping sides relative to the baffle.

It is possible that in some circumstances the aqueous solution flow rate through the carrier liquid may be greater on the stripping side of the cell. Consequently the criteria set out above, and where relevant below, will be reversed and the circulation will be in a generally clockwise direction.

It is preferred that in the regions of reduced electrostatic field that the resistance of the baffle to the passage of entrained feed and stripping solution droplets is also enhanced.

Effectively, the resistance to flow of a droplet across a baffle element is defined in terms of a "potential barrier" as a measure of the resistance to passage of the droplet in a defined direction. The potential barrier is defined as the vertical height gain required in order to pass across the baffle element. Referring again to Figure 6, the potential barrier, PA, for passage from left to right across the baffle element 8 is a function of the length LA of the baffle element about the vertical axis 6 and φA, the included angle between the side LA and the vertical axis 6. Similarly, the potential barrier, PB, for passage from right to left is a function of LB and φB as seen in Figure 3. The lengths LA and LB of the side portions 2, 4 respectively and the angles φA and φB have a direct influence on the potential barrier as defined in terms of a pure height gain needed for a droplet to pass across the baffle, the vertical spacing V between baffle elements has an effect on viscous drag of the carrier liquid and entrained droplets passing through the baffle. As the spacing V decreases, the viscous drag on the carrier liquid increases thus increasing resistance to flow through the baffle. The angle φ between the side portion and the vertical axis has an effect on the effective spacing S between adjacent side portions of adjacent baffle elements 8; the smaller the angle φ> the smaller the effective spacing S and the greater the viscous drag on the carrier liquid. However, it is stressed that the baffle elements shown in Figure 6 are shown merely for the purpose of explaining at least some of the parameters which affect the operation of a baffle arrangement in an ESPLIM cell and are not intended to be exemplary, as shown, of a baffle arrangement as used in the present invention.

In one embodiment of the baffle and electrode arrangement of the present invention, the potential barrier provided by the baffle per se is raised at regions in the cell where the flow of carrier liquid caused by the feed stream is strongest in a particular direction. Simultaneously, the electrostatic field in these regions may also be reduced or removed. Thus, in the case as described above where there is a higher flow rate of feed solution causing a downward flow of carrier liquid on the feed side and a consequent upward flow of carrier liquid on the strip side, the overall flow being in a generally anti-clockwise direction, a greater potential barrier and lower electrostatic field is formed at the upper end of the baffle on the strip side and a greater potential barrier and lower electrostatic field on the feed side at the lower end of the baffle to impede droplet flow across the baffle elements in these regions.

Therefore, the baffle of the baffle and electrode arrangement according to the present invention may be asymmetric with regard to at least one of the parameters listed below on either the feed or strip cell sides. Referring again to Figure 6 :

a) the length of the sides LA and LB may not be equal ;

b) the angles φA and φB may not be equal;

c) the spacing V between baffle elements along the vertical length of the baffle may vary;

d) baffle element side portions may exist only on the feed cell or strip cell side in particular regions of the baffle arrangement;

e) the shape of some or all of the baffle element side portions may not be linear but may be curved for example .

According to a second aspect of the present invention, there is provided an electrostatic pseudo-liquid membrane cell for the extraction of a solute from an aqueous solution having a baffle and electrode arrangement according to the first aspect of the present invention.

According to third aspect of the present invention, there is provided a baffle arrangement for an ESPLIM cell for the extraction of a solute from an aqueous feed solution, the baffle arrangement comprising a plurality of baffle elements in substantially vertical array and characterised by the array being asymmetric with respect to a substantially vertical axis along which the baffle elements are disposed.

In order that the present invention may be more fully understood, examples will now be described by way of illustration only with reference to the accompanying drawings, of which:

Figure 1 shows a schematic arrangement of apparatus showing the basic arrangement and operation of a prior art ESPLIM cell;

Figure 2 shows a schematic arrangement of a prior art ESPLIM cell similar to that shown in Figure 1 indicating a normal flow pattern of the carrier liquid therein;

Figure 3 shows a schematic view of part of a separation apparatus having a baffle and electrode arrangement according to a first embodiment of the present invention;

Figure 4 shows a similar view to that of Figure 3 of a second embodiment of the present invention;

Figure 5 shows a similar view to that of Figure 3 of a third embodiment of the present invention;

Figure 6 shows a generalised baffle for the purpose of defining the factors involved in the operation of a baffle in minimising leakage of aqueous solutions thereacross; Figure 7 shows a schematic baffle arrangement to limit flow of aqueous liquid from the stripping side to the feed side of the cell;

Figure 8 shows a baffle arrangement similar to Fig. 7 but for limiting leakage of aqueous liquid from the feed to the stripping side of the cell;

Figure 9 shows an alternative schematic baffle arrangement which may be employed in the baffle and electrode arrangements as shown in Figs 3 to 5; and

Figure 10 which shows part of a schematic baffle arrangement of a further embodiment .

Referring now to the drawings and where Figure 1 shows a schematic cross section through an apparatus 10 for carrying out the ESPLIM method of separation according to the prior art. The apparatus 10 comprises a reaction tank or vessel 12 which is divided at its upper portion by a wall 14 into an extraction cell 16 and a stripping cell 18. At the lower end of the tank 12 there is a wall 20 which divides the tank into two receiving vessels or settling tanks 22, 24 for the purified feed solution or raffinate and, for the concentrated extractant in the stripping solution, respectively. Situated between the upper wall 14 and the lower wall 20 is a baffle 26 which allows an organic carrier liquid 28, in this case kerosene, to move freely throughout the tank 12. Electrodes 30, 32 are situated in the feed or extraction cell side 16, between which a first high voltage AC electrostatic field may be applied. Electrodes 34, 36 are situated in the stripping cell side 18, between which a second high voltage AC electrostatic field may be applied. In each of the cells 16, 18 at least one of the electrodes is insulated with, for example, a coating of polytetrafluoroethylene (PTFE) to prevent short circuiting within each cell. A controllable high tension AC supply 80 is provided for the electrodes so as to establish a desired potential therebetween. A conduit 40 is provided above the extraction cell side 16 to supply a stream of feed solution 42 which is to be purified, into the carrier liquid 28. The conduit 40 has connected thereto pump means

(not shown) and a reservoir tank (not shown) to provide a continuous supply of aqueous feed solution at a controlled rate. Another conduit 44 is provided above the stripping cell side 18 to supply a stream 46 of aqueous stripping solution into the carrier liquid 28. The conduit 44 also has connected thereto pump means (not shown) and a reservoir tank (not shown) to provide a continuous supply of stripping solution at a controlled rate. Each of the receiving vessels 22, 24 have conduits 50, 52 to enable the raffinate 54 and the concentrate 56 to be drawn off as the level in each vessel rises or as required. The raffinate and concentrate are pumped to collection vessels (not shown) for disposal, storage or further processing as required.

In operation, the apparatus 10 functions as follows and using as an example the extraction of cobalt metal ions from the feed solution 42 in which the Co ions are present at a concentration of lOOOppm in a 0. IM aqueous sodium acetate solution, the feed solution being supplied at a flow rate of 200 ml/hr into the carrier liquid. The stripping solution comprises a 1.0M solution of sulphuric acid which is supplied at a flow rate of 10 ml/hr into the carrier liquid. The diluent kerosene carrier liquid 28 has dissolved therein 10 volume% of di- (2-ethyl- hexyl) phosphoric acid (D2EHPA) extractant . An AC electrostatic field of 3KV supplied via a transformer from the mains supply is applied between the electrodes 30, 32 and 34, 36 to establish the first and second electrostatic fields. As the relatively large droplets of the feed solution 42 and stripping solution 46 fall into the extraction cell 16, they are subjected to the electrostatic fields between the electrodes 30, 32 and 34, 36 which have the effect of causing the relatively large droplets to break up into a multiplicity of microdroplets 60, 62 thereby greatly increasing the surface area to volume ratio of the two aqueous phases. In the extraction cell 16, the Co ions are extracted from the aqueous solution droplets due to the affinity of the D2EHPA thus causing the concentration of the Co-complex to rise in the extraction cell in the kerosene phase. Due to the concentration gradient so formed, the Co-complex diffuses through the kerosene through the baffle 26 towards the stripping cell 18 where the Co-complex reacts with the microdroplets 62 of the stripping solution where the Co- complex reacts with the sulphuric acid to free the D2EHPA, the Co ions reacting with the sulphuric acid and being concentrated therein. The D2EHPA then migrates back through the baffles 26 to the extraction cell 16 to establish a continuous chemical process. As the reacted droplets 60, 62 pass through the electrostatic fields under the influence of gravity, they eventually pass out of the electrostatic fields and begin to coalesce into larger droplets 70, 72 which fall into the receiving vessels 22, 24 as appropriate.

In experiments under the conditions described above, an initial feed solution of a Co concentration of 1000 ppm was purified to a concentration of 10 ppm in the raffinate 54, whilst the concentrate 56 had a concentration of 19,750 ppm of Co ions.

Therefore, it will be seen that the method makes it possible to concentrate metal ions to a level where it is both practicable and economic to extract the concentrated metal ions so as to recover and reuse the metal per se . An example of this may be uranium. It is also clear that the feed solution may be so purified as to make disposal easier and/or less hazardous. However, as noted hereinabove, small droplets of the raw aqueous feed and/or stripping solution may be carried by the prevailing flow pattern in the carrier liquid across the baffle and which serves to contaminate the product concentrate 56 or the feed solution raffinate 54. It will also be noted that the baffle 26 is symmetrical about a vertical axis and also substantially co-extensive with the electrodes 30, 32 and 34, 36.

Figure 2 shows a simplified version of the apparatus of Figure 1 for the sake of clarity. The feed and stripping streams are indicated generally by the arrows 90, 92 respectively rather than droplets as in Figure 1. Since the feed stream 90 has a substantially higher flow rate than the stripping stream 92, it tends to dominate in its effect on flow of the carrier liquid 28 within the cell 12. The effect of the feed stream 90 is to cause the carrier liquid to flow or move in a generally downwardly direction as indicated by the arrow 98, mainly due to entrainment and viscous drag by the aqueous feed droplets. In the absence of the feed stream, the stripping stream 92 would tend to have the same effect on the carrier liquid but due to the relatively much higher flow rate of the feed stream in this case, the overall effect is to promote an anticlockwise flow in the carrier liquid as indicated by the arrows 98, 100, 102 and 104. The effect of the flow in the carrier liquid in conventional ESPLIM cells is to entrain smaller droplets created by the electrostatic field and carry them across the baffle elements as described above .

Figure 3 shows a first embodiment of a baffle and electrode arrangement in simplified form. The Figure shows only the electrodes 30, 32 on the feed side; the electrodes 34, 36 on the stripping side; the baffle 26; carrier liquid 28; and, schematicised feed and stripping aqueous droplets. In this embodiment the general flow direction is again anticlockwise as indicated by the arrows 200, 202, the flow being caused by the relatively much greater flow rate of the feed stream. However, the electrodes on the feed side are curtailed at their lower end 204 so that the electrostatic field generated finishes earlier. The effect of this is that the very small droplets 206 as they reach the end of the electrostatic field begin to coalesce into larger droplets 208 sooner than they would otherwise do and thus become less susceptible to entrainment and being carried across the baffle 26 by the flow 200 from the feed to the stripping side. Similarly, the electrodes on the stripping side are curtailed at their upper end 210 before the upper extent of the baffle so that the larger droplets 212 of the stripping stream are not broken up by the electrostatic field in the region where the cross current 202 is strongest, thus limiting leakage of stripping solution from the stripping to the feed side of the cell . In this embodiment, the uppermost extent of the electrodes on the feed side may extend beyond the baffle and the lowermost extent of the electrodes on the stripping side may extend beyond the baffle.

Figure 4 shows a second embodiment of the present invention wherein both pairs of electrodes are curtailed at both their upper and lower ends such that larger droplets 220 prevail in the regions where cross flow currents are strongest. In essence, this embodiment functions in a similar manner to that of Figure 3. However, this arrangement is less efficient as there is less electrode height for the extraction and stripping phases of the separation process to occur. Against this proviso however, it is to be noted that this arrangement may be a preferred form of the invention with regard to electrode configuration if the available cell vessel 12 height is sufficient to allow complete extraction and stripping whilst still allowing for the shorter electrodes relative to the baffle height.

Figure 5 shows a third embodiment of the present invention which is a modification of the arrangement shown in Figure 3. In this embodiment, the baffle 26 is provided with greater resistance to flow at its upper end 230 on the stripping side and at its lower end 232 on the feed side. The mechanism by which the resistance to flow of carrier liquid by the baffle is enhanced has been explained in part hereinabove. Figures 7 to 10 below explain the construction and operation of the baffle in more detail .

Figure 7 shows an arrangement of baffle elements 8 which increase the potential barrier presented to droplets when moving from the stripping side 18 to the feed side 16 and where the length LB of the stripping side portion 4 is greater than the length LA of the feed side portion 2. Thus, PB is greater than PA; the angles φA and φB remaining equal . This formation is seen at the upper end of the baffle 26 in Figure 5.

Figure 8 shows the reverse arrangement to that of Figure 7 where the potential barrier PA is greater than PB thus reducing leakage from the feed side to the stripping side. This formation may be seen at the lower end of the baffle 26 in Figure 5.

Figure 9 shows a complete baffle arrangement for a baffle and electrode arrangement according to the present invention such as may be employed in the ESPLIM cell shown in Figure 3 for example. As shown schematically in Figure 3 the prevailing carrier liquid flow is in a predominantly anti-clockwise direction with left to right flow 200 at the lower end of the baffle; right to left flow 202 at the upper end of the baffle and generally vertical flow therebetween. Therefore, at the upper end 120 of the baffle arrangement on the strip side, the potential barrier is relatively high by use of longer side portion 4 lengths LB and relatively close spacing V, whereas on the feed side 122, the lengths LA of the feed side portions 2 are shorter and have a greater spacing V. At the lower end 124 of the baffle arrangement on the feed side and on the stripping side 126, the baffle element portions are reversed since the principal flow direction of the carrier liquid is from left to right. In the middle portions of the feed side 128 and strip side 130 where flow could be in either direction but at a substantially lower flow rate, the baffle element portions on both the feed and strip sides are of substantially equal length but shorter than the maximum lengths employed. Half-baffle elements have also been utilised in Figure 9 to raise the potential barrier on the strip side at the top of the cell and on the feed side at the lower end of the cell .

Although in Figure 9 the longer sides and the shorter sides have been shown as all being of equal length in each case, this is not necessarily so and has only been depicted in this manner for illustrative purposes. The side lengths may be any that experiments deem necessary. Similarly, spacing between baffle elements has been shown at only two different pitches, however, again the spacing V may be any that experiments show to be most advantageous .

Figure 10 shows a variation of the preceding Figures where not only the side portion length has been varied but also the angles φA and φB where φA is shown as being greater than φB thus presenting a greater potential barrier to flow from the stripping side to the feed side of the ESPLIM cell. It will be noted from Figure 10 that where the angle between the side portion and the vertical axis 6 decreases, although the vertical spacing or pitch V at the axis 6 remains constant, the relative effective spacing S, measured normal to the plane of the side portions, between the side portions decreases on that side and increases the resistance to flow. Therefore, to an extent, the effective spacing S and the angle φ between the side portion and the vertical axis 6 are interrelated.

Although Figure 10 above refers to a baffle portion to limit flow from the stripping to the feed side, this may clearly be reversed to limit flow from the feed to the stripping side.

The baffle formation shown in Figure 10 may be employed as appropriate in the cells as depicted in Figures 3 to 5 for example .

Claims

1. A baffle and electrode arrangement for an electrostatic pseudo liquid membrane cell for the extraction of a solute from an aqueous feed solution into an aqueous stripping solution via a non-aqueous carrier liquid, the baffle and electrode arrangement being such that an electrostatic field produced by the electrodes is reduced or removed at least in a region or regions of the cell where bulk flow of a carrier liquid between feed and stripping sides of the cell are at a maximum.

2. An arrangement according to claim 1 wherein the electrodes on a side of the cell having a higher aqueous flow rate passing through are terminated above a lower extent of the baffle.

3. An arrangement according to either claim 1 or claim 2 wherein the electrodes on a side of the cell having a lower aqueous flow rate passing through are terminated below an upper extent of the baffle.

4. An arrangement according to any one preceding claim wherein the electrodes on both the feed and stripping sides of the cell are terminated above a lower extent of the baffle and below an upper extent of the baffle.

5. An arrangement according to any one preceding claim wherein the baffle is asymmetric about at least one of a vertical axis and a horizontal axis.

6. An arrangement according to any one preceding claim wherein the resistance to passage of a droplet across a baffle element is measured in terms of a potential barrier, as hereinbefore defined, as the vertical height gain required in order to pass across the baffle element .

7. An arrangement according to any one preceding claim wherein the baffle of the arrangement is asymmetric with regard to at least one of the following parameters, as hereinbefore defined, on either the feed or strip cell sides:

a) the length of the sides LA and LB of a baffle element are not equal;

b) the angles ╧åA and ╧åB are not equal;

c) the vertical spacing V between baffle elements along the vertical length of the baffle is not constant;

d) baffle element side portions exist only on the feed cell or strip cell side in particular regions of the baffle arrangement; e) the shape of some or all of the side portions of the baffle elements are not linear;

f) the disposition of the electrodes relative to the baffle.

8. An electrostatic pseudo-liquid membrane cell for the extraction of a solute from an aqueous solution having a baffle and electrode arrangement according to any one of preceding claims 1 to 7.

9. A baffle arrangement for an electrostatic pseudo liquid membrane cell for the extraction of a solute from an aqueous feed solution, the baffle arrangement comprising a plurality of baffle elements arranged in a substantially vertical array and characterised by the array being asymmetric.

10. A baffle arrangement according to claim 9 wherein the array is asymmetric about at least one of a vertical axis and a horizontal axis.

11. A baffle arrangement according to either claim 9 or claim 10 wherein the resistance to passage of a droplet across a baffle element is measured in terms of a potential barrier, as hereinbefore defined, as the vertical height gain required in order to pass across the baffle element.

12. A baffle arrangement according to any one preceding claim from 9 to 11 wherein the baffle element arrangement is asymmetric with regard to at least one of the following parameters, as hereinbefore defined, on either the feed or strip cell sides:

a) the length of the sides LA and LB of a baffle element are not equal;

b) the angles ╧åA and ╧åB are not equal;

c) the vertical spacing V between baffle elements along the vertical length of the baffle is not constant ;

d) baffle element side portions exist only on the feed cell or strip cell side in particular regions of the baffle arrangement;

e) the shape of some or all of the side portions of the baffle elements are not linear.

13. An electrostatic pseudo-liquid membrane cell for the extraction of a solute from an aqueous solution having a baffle arrangement according to any one of preceding claims 9 to 12.

14. A baffle and electrode arrangement for an electrostatic pseudo liquid membrane cell for the extraction of a solute from an aqueous feed solution substantially as hereinbefore described with reference to the accompanying description and Figure 3 ; or Figure 4 ; or Figure 5 ; or Figure 7 ; or Figure 8; or Figure 9; or Figure 10 of the drawings.

15. A baffle arrangement for an electrostatic pseudo liquid membrane cell for the extraction of a solute from an aqueous feed solution substantially as hereinbefore described with reference to the accompanying description and Figure 7; or Figure 8; or Figure 9; or Figure 10 of the drawings.

16. An electrostatic pseudo-liquid membrane cell for the extraction of a solute from an aqueous solution having a baffle arrangement substantially as hereinbefore described with reference to the accompanying description and Figure 7; or Figure 8 ; or Figure 9; or Figure 10 of the drawings.

17. An electrostatic pseudo liquid membrane cell having a baffle and electrode arrangement for an electrostatic pseudo liquid membrane cell for the extraction of a solute from an aqueous feed solution substantially as hereinbefore described with reference to the accompanying description and Figure 3 ; or Figure 4 ; or Figure 5 ; or Figure 7 ; or Figure 8; or Figure 9; or Figure 10 of the drawings.