Orbite Technologies Inc EORBF

Procédé similaire ? Relations avec la baisse ?

[charlot73]

Serious observations

 

For iron solvent extraction, the earlier publication has a two stage process, whereas the PEA uses a single stage, which is significant improvement in terms of operational flexibility and cost. The big issue with the iron solvent extraction circuit is that stripping achieves an iron concentration of only 68 g/L and the loaded strip solution undergoes evaporation to raise this to 144 g/L. At full production (80.2 tonnes of hematites solid per hour) this gives about 400 tonnes per hour of solution flow to pyrohydrolysis. This number is significant in that typical pyrohydrolysis installations in the steel industry treat no more than 10 m3/hour, with 25 m3/hour being considered the maximum practical size, so Argex is planning an installation at full production which is 16-40 times larger than anything yet built.

In analysing the PEA, it was further noted that the acid-brine solution regenerated by the iron pyrohydrolysis is combined with other process streams such as evaporated titanium hydrolysis filtrate and acid recovered from the pyrohydrolisis of the process bleed stream, in order to regenerate the leaching solution targeted to contain 6N HCl and 225 g/L MgCl2.

Unfortunately, the laws of chemistry preclude that. The Vapour-Liquid-Equilibrium curves for HCl over solutions for varying strenghs of hydrochloric acid and magnesium chloride shows that the solution postulated by Argex PEA would lie between 1.92 and 2.74 MgCl2, and 6N HCl is between 15 and 18% HCl. As can been seen from these curves, it would be impossible to absorb the acid as proposed in the Argex PEA.

The result is that to recover th HCl, the off-gas from pyrohydrolysis will need to be scrubbed conventionally with water to generate 18% HCl. By definition, if there is 18% HCl, then there must be 82% water, and in order to maintain the circuit water balance, this water will have to be evaporated. Thus, the evaporation duty of the CTL flowsheet will be greater than that assumed in the Argex PEA, and consequently, both capital and particularly the operating costs will most probably be significantly higher than indicated in the PEA.