FR2501723A1 - PROCESS AND APPARATUS FOR THE RECOVERY AND CONCENTRATION OF NON-FERROUS MATERIALS SUCH AS ZINC AND LEAD - Google Patents

Abstract

PROCESS AND APPARATUS FOR THE RECOVERY AND CONCENTRATION OF NON-FERROUS MATERIALS SUCH AS ZINC AND LEAD. THE PROCESS OF THE INVENTION INCLUDES A FIRST STAGE OF REDUCTION BY CARBON OF THE CARBON COMPOUNDS WITH VOLAUSE OF ZN AND PBO, THE NECESSARY TEMPERATURES BEING REACHED BY PARTIAL COMBUSTION, WITH AIR AND OR OXYGEN, CO CARBON, MINERALS OF ZN AND PB WITH THE APPROPRIATE GRANULATION; AND A SECOND STAGE OF OXIDATION OF ZN OBTAINED IN THE GASEOUS PHASE, BY AIR AND OR OXYGEN. THE PROCESS IS CARRIED OUT IN A TRUNCONIC REACTOR CONSTITUTED BY A METAL ENCLOSURE 2 LINED INTERNALLY WITH A REFRACTORY PRODUCT 3, AND CAN ROTATE AROUND ITS AXIS VERTICALLY. THE REACTOR IS EQUIPPED WITH A DRAIN HOLE 5 AT ITS BASE FOR LIQUID SUBSTANCES. THIS PROCESS IS USED TO RECOVER OR CONCENTRATE ZN AND PB FROM PRIMARY OR SECONDARY RAW MATERIALS.

Description

Method and apparatus for recovery and concentration

  non-ferrous materials such as zinc and lead.

  The present invention relates to a method of

  of non-ferrous metals, such as lead and zinc, by volatilisation or fumigation, at a

  the appropriate temperature, products which contain such

  variable percentage in the form of oxides or sulphides.

  of said metals, and the apparatus for carrying out said

  is another aspect of this invention.

  Theprodults to be used can be either

  primary raw materials (ores) or raw materials

  secondary (steelworks fumes, mineral residues and

metallurgical slag).

  The currently most important processes

  in the area of volatilization to recover, or concentrate

  ter, non-ferrous metals such as zinc and lead

be described below.

  Waelz furnace process: in this process, the filler, which contains zinc (at most 30 to 35%), lead, and other metals (in a smaller proportion) is mixed with coke dust or anthracite dust in a proportion of 18 to 25% by weight, and is charged in a conventional rotary kiln lncllnated from 2 to 4 by

compared to the horlzontale.

  An appreciable amount of useful metals is thus recovered. The main drawbacks are the considerable volume of installations, with very large areas of exchange between the volumes to be treated and the atmospheric air, so that the interesting heat can be recovered.

only partially.

  The oven-cyclone process is a process in which the filler mixed with the coke dust is sent to a cylindrical oven-cyclone where it is brought into contact

  tangentially with preheated air. The fumigation is real-

  in an adjacent oven, which is usually an arc furnace

  electric. In the electric arc furnace non-combustible

  volatiles can be collected in a white phase that

  is separated from the slag. Therefore, energy consumptions

  siderables are in play. In addition, the load must be dried

  completely and should have a maximum granulation of

  limètre. Surprisingly, it has now been found that the disadvantages of conventional technology can be eliminated by working in a single reaction zone.

  medium with partially oxidizing and partial character and reducing.

  As a suggested process, it is possible to use high quality coal and small coal in place of natural gas or coke. These advantages do not impede the achievement of a satisfactory heat distribution mode and the establishment of suitable physicochemical conditions.

  for the evolution of interesting reactions.

  A first object of the invention is a process which provides the mixture of products containing Pb and Zn in the form of their oxides or of their salts (sulphates, sulphides, silicates, aluminates and others) with a product containing carbon, the partial combustion carbon giving carbon monoxide (CO). The course of the process is carried out so as to

have two stages.

  The first stage is a direct reduction of the

  zinc, from its oxides or salts, with volatilization

  zinc and lead oxide contained in the feedstock. This reduction takes place at the expense of the carbon that

  is contained in the carbon product used.

  The second stage is a gas phase oxidation

  zinc produced in the first stage, by air and / or oxy-

  gene, which is carried out concurrently with the formed zinc vapors. o The non-volatile fraction of the feed, which is essentially composed of CaO, SiO 2, and FeO, that is to say, in the form of oxides, and which contributes to forming the slag, will have its concentrations in various elements selected to produce a slag at a melting temperature of not more than 1200 C, so that non-volatile

  leave the reactor in the liquid phase.

  For the latter reason, it will be necessary to provide appropriate additions to commodities if the concentrations of the components are not sufficient.

250 1723

  to fulfill the conditions specified above.

  During the course of the first stage, under determined and imposed treatment conditions, the metallic lead can be obtained by the reaction: PbO + CO -> Pb (liquid) + C02 The metallic lead thus obtained will mix with the slag and be separated by gravity. Carbon monoxide collected around the axis of rotation entrains volatilized products upwards and is burned with oxygen so well

  that additional heat can be supplied to the process.

  The treatment temperatures vary between 1100 and 1600C.

  A second object of the invention is the apparatus

  to carry out the process in question.

  Refer to Figures 1 and 2 of the board

attached.

  The reactor has a frustoconical shape and is

  of one or more frustoconical parts, which are

  They are replaced by their outer or inner enveloping curved surface, and are arranged with their vertical geometric axis and can be rotated around the axis 1 axis. The reactor is formed of a metal envelope 2, which is internally lined by

a refractory layer 3.

  The angular velocity of rotation and the angle 4, between the generatrices of the internal surfaces of the walls of the frustoconical bodies (or their enveloping surfaces like this

  may be the case) and the vertical, are such that the solid phase

  charged remains, from a dynamic point of view, in equilibrium under the concurrent actions of the weight, the rotational inertia forces and the friction forces at the internal walls,

  while the liquid phase formed during the treatment is

  towards the base of the reactor which has a flow hole 5.

  The inner diameter of the larger reactor base may be from 1 to 10 meters long and preferably from 2 to 6 meters, while the inner diameter of the smaller base varies from 0.2 to 1 meter. The diameter of the drainage hole should be between 5 and 30% of the diameter of the largest base depending on the potential production of the installation, and can even reach 100 I of the diameter

  from the smallest base. The angle of the generators with the

  can vary between 10 and 60, values are preferred

greater than 20.

  The rotational speed of the conical body should be between 10 and 80 rpm. (In the case of a device consisting of more than one

  trunk of a cone, or of a curved surface enveloping the gen-

  cane or their tangents, the angle between the trunks

  consecutive tronxniques must not exceed 30).

  In addition, there are 2 to 4 pipes (nozzles) 6 and 7,

  with their end opening inside the reactor and inclining

  suitably, said nozzles being capable of being

  placed along the vertical axis so that they can

  be used both for the loading of the mineral

the and that of the fuel.

  On the other hand, one or more pipes 8, (maximum of four in number), are essentially parallel to the generatrices of the inner surface and have perforations 9 throughout their length or almost, said perforations being evenly spaced if desired, and air and / or oxygen

  are insufflated continuously and possibly preheated.

  The speed of the current of the combustion auxiliary has a

  radially centrifugal poser and a component tangential to the trajectory of the point of impact on the wall, which

  is consistent with the movement so as not to interfere with the conditions

  dynamics of the load present in the state

liquid, in the solid state.

  Finally, a central pipe 10 is provided for injecting the stream of the combustion aid to both burn the oxide / carbon that has formed and to

  cause oxidation of Zn vapors.

  The load can be a primary raw material

  mayor (an ore) and / or secondary raw material (steelworks fumes, residual treatment sludge and others)

  which contain lead and zinc in varying proportions.

  such as 1% and more. The granulation will be between 0.01 mm and 5 mm. The products can be introduced at the top of the reactor after having already been mixed with the fuel, the latter also being of the fine-grained type, or they can be fed separately by the aforementioned pipes so as to obtain a sufficient release of heat, in accordance with

  temperatures, and also to provide a reduced environment.

in the upper part.

  In the bottom of the furnace, by pipes not yet used Until this stage, products containing carbon are added to ensure the conditions of treatment (reduction)

  and the thermal conditions, necessary.

  The amount of carbon to use depends on the amount of zinc and varies from 8 to 25% of the load and

preferably from 15 to 20%.

  As a combustion aid, air, optionally preheated to 600 ° C. and enriched with oxygen, is used.

  or also pure oxygen, possibly preheated to 2000C.

  It must be remembered that the process speed is very high because of the very large contact area between the individual phases, which is a direct consequence

  both the fine granulation of the laden product and the movement

  rotation of the reactor. The consumptions that can be

  predicted are almost stoichiometric.

  The present invention is illustrated by the example

  full descriptive and not limiting thereafter.

EXAMPLE

  The raw material is steelworks smoke containing 20% zinc and 3.5% lead. The reactor is a

  downward tapered container made up of an enve-

  lined sheet of metal foil internally coated

  The dimensional specifications are as follows: 530 Dilameter of the largest base of the cone (upper section) 3800 mm Diameter of the smallest base of the cone (lower section) 800 mm Height of the cone frustum 5000 mm Angles of the generators of the cone cone with the vertical 45 and 100,

respectively (top and bottom).

  The characteristic parameters of the treatment are as follows: Cone rotation speed 20 tp] Oxygen flow 5 m3 normal per min Feeding speed for the meal: 4 kg per min Feeding speed of the load: 65 kg per The mixture is mixed with 0.10 kg of coke per kg of

  coke being intended for use as an auxiliary coke.

  iary. Under these conditions, an oxide containing 60% Zn and 10% Pb is obtained, with a production of 20 kg per minute and yields of Zn and Pb of the order of 95-95% and more.

Claims (6)

  1%% for / recovery or concentration of Zn and Pb from primary or secondary raw materials   including the mixing of the prodult with the coal, the combustion   partial carbon to obtain c0O, characterized in that it is carried out in two stages, in the first stage there is a direct reduction of zinc by reaction with   the carbon content of carbon compounds and the volatility   of zinc and lead oxide, the temperatures   necessary erasures being achieved by partially burning with air and / or oxygen carbon in CO, products containing zinc and lead having the appropriate granulation; in the second stage Gas phase oxidation of the zinc obtained in the first stage medium of air and / or oxygen.   2. Method according to claim 1, characterized by   that temperatures vary from 1100 C to 1600 C.   3. Process according to claims 1 and 2, characterized in that   the fact that the granulation of the solid products of   The charge is between 0.01 mm and 5 mm.   4. Method according to any one of the claims   1 to 3, characterized in that the auxiliary combustion,   air and / or oxygen is preheated to a taken between 200 and 6000C.   5. Apparatus for carrying out the process according to the   cation 1, characterized in that it is frustoconical and   is composed of one or more truncated cones possibly   replaced by their respective enveloping surfaces   internal or external, the reactor being composed of a reactor   loppe of metal (2) lined internally With products   refractories (3) and rotatable about its geometric axis.   trolley (1) arranged vertically, a drainage hole (5)   being arranged in the bottom of the reactor so that   loaded solid dusts, under the effect of the various forces, adhere to the internal walls of the reactor and that the substances   formed fluids can flow to said flow hole   (5), the inner diameter of the largest base of the cone being chosen between 1 and 10 meters, the inner diameter - 2501723   from the smallest base being from 0.2 to 1 meter, the diameter of the flow hole (5) being from 5 to 100% of the inner diameter of the smallest base of the cone, the angle (4) of the generators of the with the vertical being between 10 and 60, and the rotational speed of the reactor between 10 and 80 revolutions per minute. 6. Apparatus according to claim 5, characterized in that the generatrices of the conical surfaces must not have relative to each other an inclination lO greater than 30.