This invention relates to a method of, and apparatus for, treating a particulate material with liquid. A particular, but not sole, application of the invention is to a method of, and apparatus for, washing of metal powders, such as copper powder.

Many particulate materials which are used in industrial processes contain contaminants which should not be allowed to remain in the particulate material. Thus, some process for washing or treating the particulate material is required before it is used in an industrial process.

Metal powder, such as copper powder, contains a number of contaminants, such as oxides and the like.

According to a first aspect of the present invention, in a method of treating particulate material, the particulate material is caused by- vibration to move along a channel member arranged in a helical manner on a vertical column from an input region of the channel member to a discharge region thereof which is at a higher level than the input region and liquid to treat the particulate material flows along the channel member in the direction towards the input region thereof.

By arranging for the particulate material to move along the channel member from the input region to

a discharge region, which is at a higher level than the input region, the liquid can flow, due to gravity, down the channel member towards the input region thereof in counterflow to the direction of movement of the particulate material. In this way, the particulate material, which is moving forwardly along the channel member in the direction towards the discharge region thereof, is thoroughly contacted by the liquid, which is flowing in the opposite direction thereto, so that the liquid can treat the particulate material.

The time taken for the particulate material to move along the channel member from the input region to the discharge region may not be sufficient to adequately treat the particulate material with the liquid and so it is convenient for the particulate material to be caused to move, in turn, along a multiplicity of channel members arranged in a helical manner on the column and each channel member has liquid flowing along it towards its input region. Thus, by increasing the number of channel members along which the particulate material moves, in turn, the time during which the particulate material is in contact with liquid is increased. It is convenient to collect the liquid which flows along each channel member adjacent to the input region of the channel member so that different liquids can flow along different channel members thereby providing different treatment for the

particulate material during its passage along the channel members. On each of the channel members the particulate material is moving upwardly in the opposite direction to the liquid which is flowing down the channel member.

According to a second aspect of the invention, apparatus comprises a vertical column structure; a channel member mounted in a helical manner on the column structure; means for introducing particulate material on to an input region of the channel member; means for vibrating the channel member to cause said particulate material to move along the channel member to a discharge region thereof, which is at a higher level than the input region; means for introducing liquid to the channel member adjacent the discharge region and means for collecting liquid adjacent the input region of the channel member.

The vertical column with the channel member mounted on it is subjected to vibration which has a vertical component and a radial component and this causes the particulate material to move along the channel member from the input region to the discharge region, which is at a higher level than the input region.

The liquid is introduced into the channel member adjacent the discharge region so that it contacts the particulate material as the particulate

material moves along the length of the channel member. The liquid is collected adjacent the input region of the channel member.

Three factors influence the efficiency of the treatment process. The first factor is the amplitude of the vibrations applied to the channel member and the column structure and the ratio of the vertical component and the radial component so as to govern the rate of travel of the particulate material up the channel member. The second factor is the rate at which the particulate material is introduced on to the input region of the channel member, i.e., the thickness of the layer of the particulate material on the channel member; and the third factor is the quantity of liquid which is allowed to flow down the channel member. It is convenient for a multiplicity of channel members to be mounted in a helical manner on the column structure in substantially end-to-end relation and wherein, except for the uppermost channel member, the discharge region of each of the other channel members to overlie the inlet region of the adjacent channel member whereby particulate material discharged from the discharge region of each of the other channel members falls on to the inlet region of the adjacent channel member. With this construction, the particulate material moves along one channel member and falls from the discharge region thereof on to the

inlet region of the adjacent channel member. The particulate material moves along each of the multiplicity of channel members, in turn, and, by arranging for it to fall from the discharge region of one channel member to the inlet region of the adjacent channel member, it enables a liquid collection duct to be located beneath the discharge region of each channel member to collect liquid from the input region of the adjacent channel member. In this way, the liquid applied to each channel member is kept separate from the other channel members. The liquid which has been collected can be tested to determine its make-up, thereby indicating the condition of the particulate material.

A weir is located between each liquid collection duct and the input region of the adjacent channel member to prevent particulate material from entering into the liquid collection duct.

In order that the invention may be more readily understood, it will now be described, by way of example only, with reference to the accompanying drawings, in which:-

Figure 1 is a front elevation of apparatus in accordance with the present invention;

Figure 2 is a side elevation;

Figure 3 is a detail of part of the apparatus; and

Figure 4 is a diagrammatic view illustrating one embodiment of the method of employing the apparatus shown in Figures 1 to 3.

Referring particularly to Figures 1 and 2, apparatus in accordance with the present invention comprises a vertical column structure 1 which includes a vertical hollow cylinder 3. The column structure includes suspension units (not shown) for the hollow cylinder and a pair of vibration motors 5 are mounted on the upper end of the cylinder. Mounted on the outside of the cylinder 3 are a multiplicity of channel members 7 each arranged in a helical manner on the cylinder 3. The channel members are arranged in substantially end-to-end relation except that the upper end of each channel member overlies the lower end of the adjacent channel member located above it. As can be seen in more detail in Figures 1 and 3, the upper end of a channel member 7A overlies the lower end of the channel 7B which is otherwise located above the channel member 7A.

The lowermost channel member extends upwardly from an open bowl 9 mounted at the base of the cylinder 3. The upper end of the uppermost channel member leads from the cylinder to a discharge pipe 11.

As can be seen in more detail in Figure 3, a liquid collection duct 13 is mounted beneath the upper end of each channel member, apart from the uppermost

channel member, and the duct leads to a pipe 15. Adjacent the duct 13 on the lower end of the channel member 7B there is an upstanding weir 17.

A nozzle 19 connected to a liquid supply pipe is located adjacent the upper end of each of the channel members. The liquid supplied to the nozzles may be water, in which case the water may be supplied on a common pipe 21 with control valves 22 controlling the flow to each nozzle. On the other hand, different liquids may be applied to different channel members, as will be described later.

A feed hopper 23 is connected via a vibratory conveyor 25 to the bowl 9.

In use, particulate material to be treated is fed from the hopper 23 via the conveyor 25 into the bowl 9. The vibration motors 5 are operated to apply vibration of, say, 25Hz to the vertical column supporting the channel members. The vibration has a vertical component and a radial component which is greater than the vertical component and, as the channel members are arranged in a helical manner on the cylinder, the particulate material begins to move upwardly from the bowl 9 from an input region of the lowermost channel member along the channel member to the discharge region at the upper end thereof. The particulate material then falls from the discharge region of the lowermost channel member on to the input

region of the channel member which, apart from the input region, is above the lowermost channel member. The particulate material continues to move upwardly along the second channel member and, at the upper end of this channel member, the particulate material falls from the discharge region on to the input region of the adjacent channel member. Eventually, the particulate material arrives at the top of the column and is discharged through the pipe 11.

A liquid to treat the particulate material is applied via the nozzles 19 to each of the channel members. The liquid is applied adjacent the upper end of the channel member and flows down the channel member towards the input region thereof, i.e., in the opposite direction to the movement of the material up the channel member.

Again, referring to Figure 3, it will be appreciated that liquid flowing down the channel member 7B builds up against the weir 17 until sufficient liquid is present for it to flow over the weir into the duct 13 and out of the pipe 15. The weir prevents the particulate material from entering the duct 13.

Referring now to Figure 4, a particular arrangement is shown for treating copper powder in order to remove contaminants. The apparatus has ten channel members 7 arranged on the support structure and, on each of the lowermost two channel members, the

copper powder is subjected to a treatment with brine which flows into the bowl 9. The next two higher channel members are each supplied with water so that the liquid discharged from these two channel members is a mixture of water and brine. The next two channel members moving up the column are treated with ammonia solution and the liquid leaving these channel members is a mixture of water and ammonia. The next three channel members are each supplied with water to remove all traces of ammonia from the powder and the liquid collected at the collection ducts for each of these channel members is a mixture of water and ammonia. Finally, the powder on the uppermost channel member is treated with de-mineralised water. It will be seen, therefore, that, as the powder makes it way up the column structure to the outlet discharge pipe 11, it is treated successively with different liquids to remove unwanted contaminants. The washed copper powder is discharged through the pipe 11. The liquids which are collected from the channel members may be allowed to go to drain, but it is convenient to analyse samples of these liquids to ascertain whether or not the powder is being correctly treated as it moves up the channel members.

If required, the cylinder 3 with the channel members mounted on it can be enclosed by an outer cover sealed to the discharge 11 and the conveyor 25 so that

an inert or other atmosphere can be contained within the cover.

In a practical embodiment of the invention, referred to here by way of example only, the hollow cylinder 3 may be 186 cm high, the outside diameter of each channel member 7 may be 68 cm and the inside diameter 53 cm.