LOW ENERGY PROCESS FOR ELECTROLYTIC TITANIUM METAL PRODUCTION

Objetivo

The production of titanium metal is carried-out by electrolysis. A new design cell allows to produce pure titanium metal from titanium tetrachloride (TTC). The main characteristic of the new process are:
1) dissolution cell is separated from extraction cell.
2) high TTC dissolution rate
3) high operating temperature
4) electrolyte inexpensive and easy to handle
5) continuous operation process.
In comparison with the traditional processes (Kroll-Hunter) the new process innovative aspects are:
A) less energy consumption
B) continuous operation
C) one plant instead of two
D) high quality of the final product
E) less pureness of the required raw material
F) high automation level.
EMG work object is to design, construct, start-up and give demonstrative tests of a plant for the production of 400 kg/day of metallic titanium by using an electrolytic process in molten alts. Here we analyse the second stages of the development of this project.
EMG process uses titanium tetrachloride as raw material, and if it is available, titanium scrap, since the intrinsic refining capabilitites of the electrolytic process. It allows to obtain a product with higher quality compared to one obtained from the thermochemical processes currently in use, due to the lower overall energy consumption and labour requirement since the process is continuous and with a high degree of automation.
EMG had to solve some plant engineering problems related to the thermodynamic properties of the compounds involved in the process and to the aim of constructing a plant having a simplicity of operation comparable to that of aqueous solution tankhouses. Because of the high reactivity of the raw material and intermediary products with oxygen and nitrogen, the process has to be conducted under vacuum and in an inert atmosphere. So EMG had to design a plant, operating in these conditions, which guarantees vacuum tightness and allows introducing and extracting of materials form the production cell reducing air entrance to the lowest degree as possible.
The plant has been designed so to obtain a continuous production by using easily removable and replaceable electrodes and to guarantee the maximum versatility that is a wide opportunity of changing the process operating parameters and the geometrical ones.
The plant has been projected as a modular system, consisting of various units having a peculiar function. The electrolytic cell consists of a crucible made of carbon steel containing the molten bath of sodium and titanium chlorides.
It is externally coated with some refractory layers housing the heating electrical resistances so to prevent the pollution of the bath from the insulating material, to avoid the resistances from contacting the anodic gases and to support the crucible.
The cell performs only the role of conaining the molten electrolyte and the electrodes while it is the external shell, water cooled, that confines the internal inert atmosphere and the gases produced in the process (chlorine).
The operating parameters of the process have been analysed and defined and so the material and energy exchanges of the system with the external have been evaluated.
The single units of the plant and the auxiliary equipments (electric heating system, electric electrolysis system, argon, line, vacuum line, chlorine line, titanium tetrachloride line, hydraulics, cooling water system, dry air system) have been designed.
The construction of the elements of the plant was performed by external suppliers and by Ginatta workshops.
GENERAL FEATURES:
The plant will comprise one unit, the unit will include:
- one PRECHAMBER for entering in materials (ex. titanium chips, make up salts, etc.) and processing devices. A pre-heating and deydrating furnace is installed here.
This prechamber is used for changing atmosphere from the outside to the inside: for this, one vertical shutting door at each end of the prechamber is installed.
- one COOLING PIT, close to the crucible, for electrodes stand-by, in this pit the stripper for cathode sponge and the sponge mill is placed.
- one CHAMBER with one CRUCIBLE; here EXTRACTION and DISSOLUTION CELLS are placed. The chamber inside is divided by opening covers into two volumes:
the electrolytic cells, in the lower volume, can operate at temperatures up to 1100 C with current intensity up to 30.000 A.
In the upper volume, at temperatures in the 100-150 C range, a manipulator performs the handling operations of electrodes, realizing a continuous production.
Windows allow vision inside the chamber and into the cells, during electrochemical processes. Production of titaniun is performed with simplicity of operations.
Electrode connectors are by-weight-actuated type.
Thick insulation and effective cooling system will maintain surface temperature of external structures at less than 50 C.
To provide insulation between bath upper surface and vault of chamber the lids will be included in the upper part of the electrode structures; auxiliary lid will cover the position of extracted electrode. - POSTCHAMBER, with one vertical shutting door.
The postchamber shall be used for atmosphere changing procedure and for TRANSFER DEVICE (TRANSFERT) maintenance.
Handling operations are performed by a two degree of freedom transfer (longitudinal and vertical displacements). This item is driven by a mechanical gears and chains systems actuated by outside electric motors.
PRODUCTIVITY:
The productivity of the plant will be 400 kgM electrolytic TI sponge/day.
ELECTROLYTICTITANIUM:
The metal produced with EMG electrochemical process, as compared with the metal produced by the processes currently in use, presents the advantages of lower production costs and higher quality. TESTWORK:
During this second phase the plant will be running and the most significant parameters will be logged by process computer and analysed to verify the results.

Programa(s)

ENG-ENDEMO C - Programme (EEC) of demonstration projects and industrial pilot projects (EEC) in the energy field, 1985-1989

Tema(s)

3.4 - INDUSTRY

Convocatoria de propuestas

Data not available

Régimen de financiación

DEM - Demonstration contracts

Coordinador

Ginatta Torino Titanium SpA

Aportación de la UE

Sin datos

Dirección

Via Brofferio 1-3
10121 Torino
Italia

Coste total