FROM LOW GRADE ORES

The invention refers to an ecologic equipment of high efficiency useful for separating and concentrating ferrous and non-ferrous metals from low grade ores. The equipment can be used both in mining industry and by companies dealing with the ecological reconstruction of mining areas in use or closed one and such, and of the mining processing companies.

The separation and recovery of the ferrous and non-ferrous metals is a rather difficult process and its main disadvantage is the fact that it requires the presence of sludge beds for secondary products that generates very big problems regarding the pollution of the environment.

In the field of separation and concentration of metals, there are known centrifugation equipment that use the centrifugal force to separate metals in containers that are rotating at very high speeds.

A disadvantage of these known solutions is that they consume a lot of energy to drive some relative big containers into rotation at high speeds. Another disadvantage of these known solutions is the low efficiency of the equipment with regard to the low concentration of the resulted metals from centrifugation. A third disadvantage of these solutions is that the equipment cannot separate metal particles smaller than a micron which means that a part of the metal particles remain unseparated and they return in the environment, namely the centrifugation equipment has a low ecologic efficiency.

There are also known equipment such as flotations that levitating the metals after they have been solubilized.

Even if they require lower investments and have a higher efficiency in separating the metals, the flotations have the disadvantage that require higher operation costs.

There are also knows separating equipment that use thiosulphate or cyanides.

The disadvantages of the equipment that use thiosulphate are: the lack of reagents, namely thiosulphate and also the fact they require a complex technology and, therefore expensive and with low efficiency because the processing time is long. Another disadvantage of the known equipment that use thiosulphate or cyanides is that they generate toxic gases .and effluents. The disadvantage of the equipment that separate and concentrate metals using cyanides is, obviously resulting from the environment high degree of pollution.

The common disadvantage of all the known equipment is that they cannot be used for low grade ores because of the low efficiency and high required energy consumption during the operation and also because they require a long reaction time.

The technical problem to be solved by the ecologic equipment for separation of metals from low grade ores, according to the invention, is to design an ecologic equipment of high efficiency cappable to concentrate ferrous and non-ferrous metals even from low grade ores that contain submicronic metalic particles.

The ecologic equipment for separation of metals from low grade ores, according to the invention, solves the technical problem by the fact that it is based on the electrostatic separation of the metalic particles using their property to give way ionic electric charge depending to their atomic mass the metals being separated according to their conductive properties.

The electrostatic separation is realized using an equipment consisting of a vertical cylindrical encloser that rotates with a variable speed that depends on the atomic mass of the metalic elements desired to be separated. At the middle, the encloser is provided with an electro valve that separates the non-purified ores from the electro-centrifuge purification system from below and with some pipes electrically isolated. Each pipe is provided with a metallic sieve feeded with direct current by a generator. As a result of the rotation of the encloser, the ore falls controlled in the isolated pipes, reaches the metallic sieves where it is subject to the electro-spry phenomenon and generates an electrostatic field. This electrostatic field loads the metallic particles differently acoording to the atomis mass of each type of metal and generates a mechanical behavior of rejection both between the metallic particles face to face and between the metallic particles and the sieves and pipes which allows their separation ad recovery.

A normal piece of material electrically uncharged has a number of positive electric charges equal to the number of neighboring negative electric charges in every area of it so that there is no part electrically charged, the material being electrically equilibrated, namely neutral. The positive charges are the nucleuses of the atoms linked in the structure of the material and they are not free to move. The negative charges are the electrons of the atoms. In conductive electric objects such as metals some of the electrons can move freely When an electrically charged object is getting close to a non-electrically-charged conductive object such a piece of metal, the force of the proximate charge generates a separation of these internal charges according to the Coulomb’s law. For instance, if a positive electric charge is brought in the proximity of a metalic object the elctrons from the metal are atracted and they move towards the positive electric charge. When the electrons leave an area this area remains positivelly charged which means it becomes unequilibrated. This generates a negative electric charged region of the object closed to the external electric charge and a positive electric chraged region at the oposite side. These are called induced electric charges. If the external electric charge is negative the polarity of the electric charged regions is reversed.

Since electrostatic separation is merely a redistribution of the electric charges of the metallic particles in the ore, this separation does not change the final total electric charge of the concentrated metal which means this metal has no electric clear charge either positive or negative. This inductive effect is reversible; in case the proximate electric charge is eliminated the attraction between the positive and negative internal electric charges make them mix again.

The electrostatic separation of metals from mixtures with various materials is suitable for relative small granulations. In case of mixtures with a granulation bigger than 5 mm the vertical currents method is used.

The ecologic equipment for separation of metals from low grade ores, according to the invention, has the following advantages:

- does not require sludge beds and does not produce toxic gases and effluents because it uses the electrostatic separation and this makes the equipment ecological;

- also allows the separation of submicronic particles because of the electrospray phenomenon produced by the metallic sieves and this generates a superior efficiency of the equipment;

- significantly reduces the operation costs because of the feeding of the sieves by a low consumer generator;

- substantially reduces the time of the metal separation and concentration process;

- allows the separation of particles with different granulation;

- Allows the processing of low grade ores because it uses electrostatic field.

Further, there is presented a practical example of the ecologic equipment for separation of metals from low grade ores related to the Figure 1, 2 and 3 which represent: Fig.l: overall view of the equipment;

Fig.2: view of one cylindrical enclosures;

Fig.3: view of the cylindrical enclosures mounted in the equipment.

The ecologic equipment for separation of metals from low grade ores according to the invention (Fig.l) consists of six vertical cylindrical enclosures 1 mounted in a hexagon (Fig.3) and connected to a electric motor 2 having a high power and speed variating device, each enclosure 1 being provided at the upper side with a storing room 9 for storing the powder of mixed ore, an electro-valve 3 mounted in the middle and some pipes 4 electrically isolated (Fig.2), each pipe 4 being provided with a sieve 5 made of stainless steel feeded with direct current by a Van de Graaff generator 6 mounted on a support 7, that separates the metallic particles which are concentrated in some storage containers 8 placed at the bottom.

The Van de Graaff genrator 6 ensures a direct current of high tension, 100000V - 1000000 V and a low amplitude 0,2 - 2 A being a small consumer.

The cylindrical encloser 1 rotates with a changing speed and its value is established according to the atomic mass of the metals that need to be separated.

The electric motor 2 ensures the rotating movement of the equipment including the cylindrical enclosure 1, namely it generates the centrifugal force.

The electro-valve 3 delimits the non-purified ores from above it from the electrocentrifuge purification system from below.

By feeding the sieves 5 with direct current an electro-spray phenomenon is generated in the area of the sieves which creates an electrostatic field that electrically charges the metallic particles. Because of their electric charges, they get a rejection mechanical behavior, namely they move getting away not only one from another but also from the walls of the pipes 4 and also from the sieves 5. After separation, the powder of ore remains above the sieves 5 and the undesirable metals remain bellow.

The higher the number of the cylindrical enclosures X is, the higher he equipment’s efficiency is.

The ecologic equipment for separation of metals from low grade ores can be also used for non-metallic ores.

The ecologic equipment for separation of metals from low grade ores can have different applications according to the material wanted to be processed, separated metals from ores in the shape of powders or liquid solutions in which case catalysts or solvents or flocculants or zeolites/ activated zeolites or polymers/ copolymers can be used to accelerate the separation process.

According to the metal types wanted to be concentrated, the rotation speed of the equipment is different.