Sea water and cyanide (acid) resistant concrete mix design

[tvar]

I have been asked to specify a concrete mix which will be in contact with wash down water which will be sea water, diluted cyanide and acids. At this point sugestions have been to use higher strength concrete 40 Mpa, use 75 mm cover to the rebar and add silica fume or a pore blocking and/or water repellant admixture. An additional constraint is that it will be placed in a desert climate even though the pours will probably be at night. Does anyone have any comment or additional infomation? Thanks