Method and device for chlorination of ore-bearing materials

Technical field

The invention relates to a method and a construction of a device for chlorination of ore-bearing materials which can be used for processing ore-bearing materials in the presence of chlorine and coke with a view to manufacturing metal chlorides as, for example, Fe, Cu, Ti, Sn, Al, Zr, V, Mo, Nb and Ta.

Actual state of the art

There is known the device and the method of manufacturing tetrachlorides of metals like titanium or zirconium, described in patent specification US 4595573, comprising a reaction chamber manufactured of refractory material and located in a closed metal jacket. In a lower part of the chamber there is a reaction zone. The present device is furnished with technological agents' distribution systems that provide heating up of the reaction chamber, filling of the reactor's jacket with gas, feeding the solid reaction mixture containing processed metal and supplying the gaseous mixture containing chlorine through the nozzle placed at the bottom part of the reaction zone. Technological pressure in the jacket exceeds positive pressure in the reaction chamber. Thus a continuous gasflow is ensured being introduced into the device through the technological agents' distribution system and carrying chlorine vapours out of the inner space of the reactor's jacket. Weak point of this chlorinator is low manufacturing capacity for the device does not provide intensive mixing of the processed metal charge and the gaseous mixture and all processes are thus carried out in a regime of laminar or natural diffusion.

There is also known a method of titanium tetrachlorid production, described in patent specification GB 836079, where highly dispersed mixture of titanium containing material and carbonaceous reducing agent passes, at the same time as a flow of chlorine, through the vertical reaction chamber, the reagents moving downwards and both solid and gaseous reaction products being removed through the bottom part of the chamber. The reaction temperature exceeds 700 ⁰ C and desirably ranges between 1000-1400 ⁰ C. The solid charge is dispersed in a carrier gas and as a rule it is introduced into the reactor separately from the chlorinating gasflow. Solid charge particles dispersed in nitrogen or carbon dioxide or monoxide with oxygen added can be introduced into the reaction chamber axially with respect to the reactor's axis while chlorine can be introduced into the reaction chamber tangentially with respect to the reactor's axis. The reactor has the form of vertically positioned cylinder. Through the hopper at its upper part the mixture of titanium ore and carbonaceous reducing agents is introduced being preliminarily crashed and treated in a grinding mill furnished with a mixing device, chlorinating gas being introduced through the apertures in the upper part of the reactor and heading downwards at a speed of 15m/sec. The lower part of the reactor is connected to a solid particles catcher whose temperature is lower than the one in the reaction chamber and from which the gaseous mixture proceeds on to the separator and condenser. Chlorides with a high melting temperature produced as reaction products create a thin layer on the walls of the reactor; creep down into the solid particles catcher whose temperature is regulated so that the chlorides with a high melting temperature, e.g. alkalis, alkali earth metals or iron chlorides can solidify and consequently can be removed from the reactor. Gaseous chlorides proceed into the next chamber the temperature of which facilitates depositing of solid compounds of ferrous and chlorine oxides which are consequently removed from the reactor through the appropriate valve. Suitable materials containing titanium are rutile, ilmenite, ferrous or titanic ores and clinker or synthetic titanium tetrachloride. For the device does not ensure intensive mixing of metal, i.e. charge and chlorine-air gaseous mixture, all processes take place in a regime of laminar or natural diffusion which results in low specific manufacturing capacity of the reactor. Other weak point is low manufacturing capacity of separate devices since it is impossible to ensure uniform distribution of chlorine and air throughout the whole section of the reactor. Another weak point of the method is high level of specific capital and operating expenditures caused by low

manufacturing capacity and the fact that the charge has to be preliminarily processed.

Nowadays specific manufacturing capacity related to 1 m ² of horizontal section of the reactor's chlorination chamber in all known types of chlorinating apparatuses, i.e. melting, shaft or fluid bed chlorinators, is practically the same. That is the reason why it is difficult to prioritize any of the devices. When attempting to increase manufacturing capacity of shaft chlorinator with a fluid bed to more than 10Ot TiCU a day serious technical difficulties occur. To distribute chlorine into the whole volume of charge layer uniformly is practically impossible in the equipment with a section larger than 3m.

The equipment whose technical substance and economically-technological effectiveness mostly resembles presented invention is a device intended for chlorination of titanium content materials described in a patent specification GB 893067. This method of processing titanium content materials in the presence of chlorine and coke comprises a number of gas line nozzles intended for introducing chlorine into the reaction zone and opening downwards to the bottom of the chamber. Nozzles are positioned in a particular distance from the walls of the reactor, from the bottom of the chamber and also one from another. As a result of gas being blown into the chamber zones of intensive turbulence are established within the reactor. The movement of the zones is demonstrated by arrows and dash lines. The device's performance description concerns processing ilmenite as titanium content material. Due to introduction of carbon, coal or coke into the reactor, consequent incineration and air blowing the inner space of the furnace is heated up to the temperature of 700-1200 ⁰ C. Through the inclined channel finely dispersed mixture of ilmenite and coke is introduced into the furnace which creates a layer inside the chamber that is being stirred up by constant air flow. When the layer reaches operating temperature the air supply is cut off and chlorine starts to be charged into reaction zone through the nozzles. The chlorine flow generates rising columns of ilmenite and carbon. Particles of ilmenite and carbon that reach the top of the columns and do not manage to react fall down back to the bed of material until they approach the nozzles and are caught and carried up by the chlorine flow again. Thus constant circulation of ilmenite and carbon upwards and downwards through the volume of processed material is

ensured. Gaseous reaction products, namely titanium tetrachloride, iron dichloride and carbon monoxide are removed from the furnace through its upper part. The patent describes processing of zirconium, tantalum or columbium as well. Weak point of this device is low specific manufacturing capacity, generally 5t/m ³ , that is limited by low linear velocity of a gaseous bubble containing chlorine through the salt melt, usually 0,3 m/sec. On this account, further intensification of processes taking place in existing chlorinators would mean extending their volume and necessary operating area which would lead to further increase in capital and operating costs.

The task of the presented invention is to introduce a method of charge chlorination and related constructional design of the reactor that would facilitate increase in manufacturing capacity.

Subject matter of the invention

The mentioned above task is fulfilled by means of the invention that presents a method of chlorination of ore-bearing materials in a reactor in the presence of chlorine and coke with a view to manufacturing metal chlorides as, for example, Fe, Cu, Ti, Sn, Al, Zr, V, Mo, Nb and Ta, whose subject matter consists in the fact that from lateral, directly opposed intake chambers of the reactor, into which powdered charge is continuously delivered together with a pressurized flow of chlorine-air mixture, the upper layer of the melt with temperature of about 850-1200 ⁰ C including suspended particles of the charge is blown at velocity of 50-500 m/sec through reaction channels directed oppositely and obliquely upwards at an angle of 30-60° into the reaction chamber, where the melt is dispersed into emulsion with active highly developed heterogeneous surface and is consequently carried away through the contact channels directed obliquely upwards at an angle of 30-60° into the discharge chamber, the gaseous reaction products being transferred to condensation in order to separate addition agents and at the same time the salt melt being continuously discharged.

The invention also includes construction of the reactor for charge chlorination comprising an enclosed-bath shaped body that is partially flooded with the melt and that is furnished with constructional elements intended for batching the charge, introducing air-chlorine mixture, discharging gaseous reaction products, heating up the melt, discharging the melt and cooling the jacket and other constructional elements dividing the inner space of the reactor whose subject matter is that inside its body there are longitudinal and transversal barriers arranged in such manner that they divide the inner space into at least one intake chamber, mixing chamber and discharging chamber which are mutually interconnected with use of a reaction channel directed obliquely upwards and a contact channel; the channels being arranged on different horizontal levels so that ascending flow of the arising melt dispersion is ensured.

Another subject matter of the invention is that reaction channels and a contact channel are arranged within the longitudinal and transversal barriers so that their chamfering assumes values of 30-60° with respect to horizontal plane.

And finally, the subject matter of the invention is the fact that inside the body of the reactor, in the area of charging hoppers and inlet nozzles there are pairs of upper and lower longitudinal barriers arranged symmetrically with respect to longitudinal axes of the reactor's body whose chamfered neighbouring surfaces create pairs of longitudinal reaction channels directed concentrically and obliquely in an upward manner, and that in the central part of the inner space of the reactor's body there are upper and lower transversal barriers whose chamfered neighbouring surfaces create a contact channel, the contact channel being arranged over he horizontal level of the reaction channels.

In a convenient version the longitudinal barriers are arranged at right angels to transversal barriers, outlet sections of the longitudinal reaction channels created within the longitudinal barriers symmetrically with respect to the reactor's axes leading into the mixing chamber and being on the same horizontal level and directed opposite each other.

The presented technical solution ensures high effectiveness, technologically sophisticated construction and unassumingness in operation of the reactor. It can be utilized in production of titanium or other nonferrous metals as well as in nuclear industry. Specific manufacturing capacity of the new reactor is about 30times higher than with existing types of equipment. Chlorination reactor with overall dimensions 4x3x2 m and a usable volume of 24m ³ , at gas consumption of 20-40000 m ³ /h, has a manufacturing capacity of 3800 tons a day. Thus the specific manufacturing capacity amounts to 156t/m3 a day, which is about 30times more than with existing technologies. Apart from that, specific unit power of individual devices manufactured according to the presented invention is also several times higher than with known chlorination apparatuses. The cause consists in easily achievable uniform distribution of chlorine within the reaction zones. Natural internal circulation of the salt melt around the lower transversal barriers against the blown gasflow is very important too. Since it is possible to processes powdered materials there is no need for charge briquetting and the processing costs are thus lowered. The new reactor can be easily automated and manufacturing costs are considerably low. Purpose and advantageousness of the described chlorination process concerning blowing powdered charge into intensive and turbulent salt-melt flow is uniquely determined by the results of practical application of autogenous processes when specific manufacturing capacity of the melting bath process amounts to 55-60 t/m ³ a day, which is about 10 times more than with existing processes taking place in a suspended phase.

Enclosed drawings description

Actual examples of the present invention's versions are schematically displayed on the enclosed drawings, where pic. 1 features a longitudinal vertical section of the reactor pic. 2 features a horizontal section of the reactor in a section plane B-B pic. 3 features a vertical section of the reactor in a section plane C-C pic. 4 features a longitudinal section of the inlet chamber intended for the powdered charge introduction in a section plane D-D

Examples of the invention's construction

The reactor comprises a closed-bath shaped body 1 lined with a refractory material or cooled by a refrigerator construction that is partially flooded with a salt- melt 2 containing chlorine. The body 1 is in its upper part furnished with devices intended for charge batching, air-chlorine mixture introduction and discharging gaseous products of chlorination, when in the described version it comprises pairs of charging hoppers 3 and inlet nozzles 4 arranged longitudinally and symmetrically to each other on one side and the central outlet nozzle 5 on the other side whose inlet section is equipped with a melt drops catching device 6 that can be in the form of a set of lamellas as it is apparent in the picture 1. In the lower part of the body 1 there is a siphon outlet 7 located at the bottom of the bath which is intended for discharging the melt. The outlet is terminated by the discharge chute 8. The body of the reactor 1 is further furnished with graphite electrodes 9 including heat exchangers 10 that serve to heat up the salt melt 2 at the start up of the reactor or to keep the melt heated at the time of lowered manufacturing capacity, e.g. in an emergency situation. Finally the body 1 is equipped with cooling exchanger circuit H that regulates the temperature of the jacket and other constructional features of the body 1 mentioned below.

Within the inner space of the body 1 in the area of charging hoppers 3 and inlet nozzles 4 there are pairs of upper longitudinal barriers 12 and lower longitudinal barriers 1_3 located symmetrically with respect to longitudinal axes of the body 1 that divide lateral inlet chambers .14 from central mixing chamber 15. The inlet chambers 14_and the mixing chamber 15 are mutually connected through pairs of longitudinal reaction channels 16 that are arranged between the chamfering of the relevant longitudinal barriers 12 and 13 on the same horizontal level and are directed concentrically and obliquely in an upward manner when the optimum angle of decline ranges from 30-60°. In the central part of the inner space of the body 1 there are upper transversal barrier 17 and lower transversal barrier 18 arranged so that they divide mixing chamber 15 from the outlet chamber 19 and they are mutually connected through the contact channel 20 leading from the mixing chamber 15 obliquely upwards at an angle ranging from 30-60°, the contact channel 20 being located over the horizontal level of the reaction channels 16.

At common operation within the framework of projected manufacturing capacity sufficient amount of heat is produced by ongoing reactions so the electrodes 9 can be switched off. The excessive heat is dissipated from the bath of the body 1 with use of the cooling exchanger circuits H located in the barriers 12, 13, 17, 18 and the exchanger 13 located in the electrodes 9. As a result of cooling a protective layer of molten slag consisting of salt-melt particles is formed on the surface of the barriers 12, 13, 17, 18 which prevents chemical or erosive damage and ensures a long term operation of the reactor at high specific manufacturing capacity.

The presented reactor operates as follows:

Bath of the body 1 is partially flooded with a melt 2 containing chlorides of Na, K, Ca, Mg, Al and Fe, e.g. used electrolytic solution of the magnesium electrolytic apparatuses. Powdered material, for example titanium cinder and coke powder, is continuously charged through the hopper 3. Through the inlet nozzle 4 the pressurized air-chlorine mixture is introduced into the reactor, the pressure amounting to1-2Atm and the mixture ratio being for example 70% Cl and 30 % air. With use of the electrodes 9 the melt is heated up to 850-1200 ⁰ C. The flow of air- chlorine mixture enters the contact reaction channels 16 that are located opposite each other and at the same time symmetrically with respect to the reactor's axes and on the outlet they create a mixing chamber 15. Gas mixture enters the reaction channels 16 at velocity of 50-500 m/sec and carries away the upper layer of the salt- melt in which there are solid particles of the charge suspended. Intensive disaggregating of the melt into an emulsion consisting of gas, melt, salt and foam concurrently takes place in the reaction channels .16 and in the mixing chamber 15. The gas mixture proceeds from the mixing chamber 15 into the transversal contact channel 20, which facilitates practically 100% utilization of chlorine from chlorinating mixture.

Gaseous products of the charge chlorination are removed form the reactor through the outlet nozzle 5 and then they proceed to condensation with a view to admixture separation, e. g. titanium chlorides separation. Depending on the level of filling up the bath with chlorides of magnesium, calcium, iron and manganese the

chemicals are continuously discharged from the reactor through the siphon outlet 7. The edges of transversal barriers \7_, 18, which create contact channels 20, are chamfered at an angle of 30-60° and favourably direct the gasflow. Thus the optimum conditions for dispersing the melt are ensured. If the angles are smaller than 30° the contact channels 20 get choked and the process of melt disaggregating is disturbed by the excessive amount of the melt included in the gaseous phase. If the angles of chamfering exceed 60° the gasflow ricochets from the melt surfaces and the intensity of disaggregating of the melt into drops is lowered, the overall surface of the salt-melt emulsion diminish and manufacturing capacity of the reactor thus decreases.

Aero-hydrodynamic and technological regime of the reactor's operation can be easily controlled by changing the amount of introduced charge and air-chlorine mixture and also by regulating the level of salt melt with use of the siphon outlet 7. Increase in the level of salt melt in the bath brings about increase in specific melt consumption at blowing through the channels 16, 20. At the same time the hydraulic friction of the apparatus increases as well as overall surface of the reacting particles, chlorination speed and specific manufacturing capacity of the reactor.

Industrial applicability

The reactor comprising constructional features presented in the invention can be used in processing of ore-bearing materials in the presence of chlorine and coke with a view to manufacturing metal chlorides as, for example, Fe, Cu, Ti, Sn, Al, Zr, V, Mo, Nb and Ta.