The regeneration of hydrochloric acid from ilmenite leach liquors

• Autores: Duncan Wills
• Localización: Industrial Minerals, ISSN 0019-8544, Nº. 554, 2013
• Idioma: inglés
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• Resumen

  • The disadvantage of using sub-azeotropic HCl for ilmenite leaching is that certain types of ilmenite are unsuited and hence the feedstock sources are more restricted. Nevertheless, the availability of ilmenite suited to leaching with 17-20% w/w HCl is sufficiently widespread to make such processes commercially viable in many parts of the world. Furthermore, the availability of proven cost effective technology to regenerate completely sub-azeotropic HCl makes such leaching processes environmentally superior to those which require concentrated HCl.

    The FBP reactor is relatively small compared to the SRP and is heated by an array of between dozens and hundreds depending on capacity of small burner nozzles. The feed liquor is poured through a tube onto a bed of oxide seeds which are fluidised by the combustion system nozzles. The feed liquor coats the seeds which move randomly around the base of the reactor and eventually find their way out of the discharge. Since the feed is introduced at about the same level as the heat, there is no temperature gradient, which combined with the random movement, results in a very long residence time compared to the Spray Roaster at the reaction temperature.

    Pyrohydrolysis using the FBP and the SRP is mature and well established with hundreds of installations worldwide in various applications, including the regeneration of spent hydrochloric ilmenite leach liquor. In the case of ilmenite leach liquors, the FBP has the significant advantage that it recovers the iron in a form which realises its maximum value and which has no environmental impact, hence the Fluidised Bed Acid Regeneration Process offers the producer of synthetic rutile a well proven, economical, and environmentally acceptable way to process spent liquor from the leaching of ilmenite with hydrochloric acid.