TECHNICAL FIELD

The present invention concerns an assembly to perform a hydrometallurgical recovery of materials from electronic boards .

BACKGROUND ART

The recovery of materials from waste electrical and electronic equipment (WEEE) represents a great opportunity in terms of both the high value of some of these materials and their re ^¬ use in components and products typical of the advanced economies (electric cars, flat screen TVs, mobile phones, magnets, batteries, fuel cells, catalytic converters, some types of solar cells) .

The demand for these materials in recent years has drastically increased and has led to a criticality in availability of the supply, resulting in higher prices.

For a correct evaluation of the above, it should be added that waste electrical and electronic equipment has an annual growth rate of 3-5%, and according to the European Waste Catalogue (EWC) , WEEE should be considered hazardous for the environment as it contains heavy metals and halogenated organic compounds.

The study of technologies for the recovery of raw materials from disused electronic devices is therefore of great interest, both in terms of suggesting an alternative to disposal in landfills or incinerators, preventing consequent pollution, and developing a selective process for the recovery of metals having a high commercial value, also in relation to the possibility of exploiting them as alternative resources. Electronic boards constitute on average 10% by weight of a PC, comprising mother board, RAM and CPU. Each board can contain up to 60 elements of the periodic table including a large proportion of noble and strategic metals such as Pt, Ag, Au, and metals with a high commercial value like Cu and Sn.

The recovery of metals and materials from electronic boards generally entails mechanical pre—treatment of the boards (grinding) using physical, gravimetric and/or electromagnetic methods, pyrometallurgical , hydrometallurgical and biometallurgical processes.

Pyrometallurgical processes at high temperature (around 1200°C) require big investments and have considerable environmental problems due to emissions into the atmosphere. Hydrometallurgical techniques, on the other hand, are generally carried out at temperatures similar to ambient temperature, with lower costs and limited emissions into the atmosphere .

Furthermore, the need for mechanical pre-treatment of the boards represents a complication in terms of both preparation of the sample and the subsequent hydrometallurgical process, to the extent that it is often necessary to design machinery able to crush the waste into appropriate dimensions.

Generally, gold is separated by a sequence of steps necessary to reach a high level of purity. Obtaining of gold and noble metals in general is the subject of various studies in the sector, and a part of the patent literature describes extraction procedures conducted with the aid of a complexing molecule synthesised for the purpose.

The Applicant has devised a hydrometallurgical process for the recovery of materials from electronic boards as described and claimed in the patent application RM2013A000549. This process has the main advantages of not entailing any grinding pre- treatment and can therefore be applied to whole electronic boards, and of guaranteeing simple direct recovery of the metal gold and the stannic oxide and/or metastannic acid after a first leaching step.

DISCLOSURE OF INVENTION

The subject of the present invention is an assembly to perform a hydrometallurgical process for the recovery of materials from electronic boards, the essential characteristics of which are described in claim 1, and the preferred and/or auxiliary characteristics of which are described in claims 2-9.

BRIEF DESCRIPTION OF THE DRAWINGS

An embodiment example is given below purely for illustrative non-limiting purposes with the aid of the accompanying figures in which:

- figure 1 schematically illustrates the assembly subject of the present invention;

- figure 2 illustrates in exploded form an embodiment of a component of the assembly subject of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

In figure 1 the assembly to perform a hydrometallurgical process for recovery of materials from electronic boards is indicated as a whole by the number 1.

The assembly 1 comprises a dissolver 2, an oscillator 3 provided with oscillating board 3a on which the dissolver 2, a vibrating screen 4, moving means 5 illustrated extremely schematically and a control unit 6 also illustrated extremely schematically are fixed in a reversible manner.

The dissolver 2 consists of an upper portion 2a with the shape of a parallelepiped designed to house the electronic boards to be processed, and a bottom portion 2b with the shape of a truncated cone and comprising a faucet 7 which can be preferably remotely operated. The vibrating screen 4 is a machine known to a person skilled in the art and therefore is not described in detail. The vibrating screen 4 must necessarily comprise at least one first screen with holes having dimensions ranging from 10 to 3 mm for recovery of unwelded components of different nature, and a second screen with holes having dimensions ranging from 0.5 to 0.01 mm for the recovery of metal Au. Preferably, the vibrating screen comprises 4 screens with holes having decreasing dimensions (10 mm; 5 mm; 0.4 mm; 0.03 mm), which retain solids with progressively smaller dimensions.

The moving means 5 are designed to move the dissolver 2 from the oscillating board 3a to the vibrating screen 4 and vice versa. The shape and components of the moving means 5 are not relevant for the purposes of the present invention as long as they are able to provide the movement described above.

The control unit 6 is designed to control at least the moving means 5 and/or opening and closing of the faucet 7 and/or activation or deactivation of the oscillating board 3a.

The vibrating screen 4 comprises an upper wall having a central opening 8 designed to receive the faucet 7 of the dissolver 2. Figure 2 shows overall by the number 9 the board holder basket which will be housed in a removable manner inside the upper portion 2a of the dissolver 2.

The board housing basket 9 consists of a supporting structure 10 and two racks 11 designed to be housed one on top of the other and in a removable manner in the supporting structure 10. The racks 10 are made of a grid structure with meshes having dimensions ranging from 1 to 10 cm.

The board housing basket 9, the dissolver 2 and the vibrating screen 4 are made of AISI 316 steel.

In use, once the racks 11 have been loaded with the electronic boards to be processed and inserted in the structure 10, the board housing basket 9 as a whole is housed inside the dissolver 2 together with a leaching solution, e.g. of HNO ₃ at 30% w/w maintaining a solid/liquid ratio of 1:3. The dissolver thus loaded is arranged on the oscillating board 3a, which is activated to favour the leaching step. Once the time necessary for carrying out the leaching step has elapsed, the dissolver 2 is moved from the oscillator 3 to the vibrating screen 4, where the faucet 7 is arranged to engage the opening 8. Once this arrangement has been obtained, the faucet 7 is opened and the leaching solution is discharged into the vibrating screen 8.

As anticipated above, the movement operations can be performed by the moving means 5 which, together with the oscillator 3 and the faucet 7, are controlled by the control unit 6.

The steps relative to the leaching and vibration screening are described in the patent application RM2013A000549 incorporated here for reference.

The elements of the assembly subject of the present invention can be arranged differently from the above description. Furthermore, the various elements of the assembly can be wholly or partly moved or operated manually.

From the above description it is evident that the assembly of the present invention allows simple effective metallurgica recovery of materials from electronic boards.