Moreover, various compounds that are formed naturally from iron ore such as iron chloride, iron hydroxide
, iron sulfate, and iron arsenate are anticipated to promote sizeable growth of the iron market over the conjecture period.
In acidic pH, iron hydroxide
is dissolved in the solution and in highly alkaline pH values, the produced iron hydroxides
are converted into Fe(OH)4-which is more soluble than ferric hydroxide.
The first is when the iron sulfide changes into iron sulphate and the second is when iron sulphate changes into orange iron hydroxide
Coprecipitation methods  such as lanthanum hydroxide [12-14], iron hydroxide
[15-17], yttrium hydroxide , and magnesium hydroxide  are also effective as other preconcentration methods to complement chelating resin technique, because both oxoanion-forming elements and cation-forming trace elements can be concentrated using this method.
Caption: Figure 5: Calcite bioclast filled by diagenetic calcite and iron hydroxide
(FeOx) replacing pyrite (AUB1010-4.80 m) (a) in transmitted light; (b) in BSE and (c) in chemical composite image (blue: Ca-rich, yellow: Fe rich; red: Si-rich); (d) bioturbation filled by pyrite (AUB1010-6.63 m) (transmitted light); (e) detail of pyrite partially replaced by iron hydroxides
(BSE); (f) celestite partially filling zone of pyrite oxidation (BSE); (g) distribution of millimetric gypsum grains replacing pyrite layer in AUB1010- 8.25 m (photo of the glass slide); (h) residual diagenetic pyrite and celestite surrounded by secondary iron sulfates, iron hydroxides
, and gypsum.
[8.] Bogdanova OM, Pashchenko IG (2004) Comparative evaluation of the effectiveness of treatment of IDA in patients with elderly drug salt and iron hydroxide
Also present were small transparent grey grains (with a distinctly higher lustre) of alkali feldspar that contained tiny metallic hematite flakes and small orange patches, possibly iron hydroxide
. When exposed to short-wave UV radiation, the calcite veins fluoresced weak reddish pink, whereas the volcanic glass remained inert (Figure 14).
Normally sulphide minerals react with oxygen and water to produce sulphuric acid and iron sulphide or iron hydroxide
. Reaction of pyrite with oxygen and water is discussed by many researchers (Banks et al., 1997; Zaihua et al., 1991; Powell, 1988).
The hexavalent chromium ions enter the solution and are separated from the iron hydroxide
precipitate as the sludge is dewatered.
We felt it appropriate to use the amorphous iron hydroxide
Several methods for hydrogen sulfide removal have been developed including biological fixation process, liquid-phase absorption with either water or NaOH solution, and adsorption on solids such as activated carbon, iron hydroxide
or oxide [3-6].