Iron residue

In the ultimate analysis it may be pointed that the aforesaid hydrolysis processes are no doubt technically very satisfactory and tolerable, but environmentally this is not the case. The different processes yield jarosite, goethite and hematite, all of which retain considerable amounts of other elements, especially, zinc and sulfur. The zinc originates mainly from undissolved zinc roast in the iron residues, and sulfur from sulfate, which is either embodied into the crystal lattice or adsorbed in the precipitate. As a consequence of the association of the impurities, none of these materials is suitable for iron making and therefore they must be disposed of by dumping. The extent of soluble impurities present in the iron residues means that environmentally safe disposal not an easy task, and increasing concern is being voiced about these problems. An alternative way of removing iron from... 

Nitrophenylpyruvic acid was reduced to oxindole using iron pin-dust-ferrous sulfate in water. The iron oxide-iron residues, after filtering and washing with chloroform, rapidly heated in contact with air and shattered the Buchner funnel [1], Previously, rapid heating effects had been observed on sucking air through the iron oxide residues from hot filtration of aqueous liquor from reduction of a nitro compound with reduced iron powder [2],... 

The use or safe disposal of the iron residues from zinc production (see Figure 7) presents a major technical problem.204 The use of chelating aminomethylene phosphonic acid extractants such as (28) and (29) to recover iron from these residues has been proposed.205 These give much higher FenI/Znn selectivity than D2EHPA but are more difficult to strip. A reductive-stripping process is proposed.187,205... 

Peacey, J. G. Hancock, P. J. Review of pyrometallurgical processes for treating iron residues from electrolytic zinc plants. Iron Control and Disposal, Proceedings of the International Symposium on Iron Control in Hydrometallurgy, 2nd, Ottawa, Oct. 20-23, 1996, 17-35. 

In a 500-cc. three-neck flask, fitted with a reflux condenser and a mechanical stirrer (Note t), is placed 45.5 g. (0.25 mole) of 2,4-dinitrotoIuene (Note 2), 85 g. (1.5 moles) of iron (Note 3), and 100 cc. of 50 per cent (by weight) ethyl alcohol (Note 4). The mixture is heated to boiling on a water bath, the stirrer is started (Note 5) and a solution of 5.2 cc. (0.06 mole) of concentrated hydrochloric acid in 25 cc. of 50 per cent (by weight) ethyl alcohol is added slowly (Note 6). The mixture is refluxed for two hours after addition of the acid is complete. At the end of this time the apparatus is disconnected and the hot mixture is made just alkaline to litmus by the addition of the calculated amount of 15 per cent alcoholic potassium hydroxide solution (Note 7). Without allowing the mixture to cool, the iron is removed by filtration and the reaction flask is rinsed with two 50-cc. portions of 95 per cent ethyl alcohol the same alcohol is used to wash the iron residue. To the filtrate is added 84 cc. of 6 N sulfuric acid the normal sulfate of 2,4-diaminotoluene precipitates. The mixture is cooled to 250 and filtered by suction. The product is washed with two 35-rc. portions of 95 per... 

Sodium carbonate is added, as before, until alkaline. After the iron residue is filtered off the filtrate is concentrated until the base crystallises. 

TriaUcylamines are capable of deprotonating (79), the products being () -allyl)FeCp(CO)2 complexes (equation 17). The abstracted proton must be oriented anti to the face of the alkene bearing the iron residue () -cyclopentene)Fp+ cations substituted with trans acidifying groups (93) deprotonate... 

Nucleophilic attack on ( -alkene)Fp+ cations may be effected by heteroatom nucleophiles including amines, azide ion, cyanate ion (through N), alcohols, and thiols (Scheme 39). Carbon-based nucleophiles, such as the anions of active methylene compounds (malonic esters, /3-keto esters, cyanoac-etate), enamines, cyanide, cuprates, Grignard reagents, and ( l -allyl)Fe(Cp)(CO)2 complexes react similarly. In addition, several hydride sources, most notably NaBHsCN, deliver hydride ion to Fp(jj -alkene)+ complexes. Subjecting complexes of type (79) to Nal or NaBr in acetone, however, does not give nncleophilic attack, but instead results rehably in the displacement of the alkene from the iron residue. Cyclohexanone enolates or silyl enol ethers also may be added, and the iron alkyl complexes thus produced can give Robinson annulation-type products (Scheme 40). Vinyl ether-cationic Fp complexes as the electrophiles are nseful as vinyl cation equivalents. ... 

Metal ion impurities in spent acid impose different recovery problems. For instance, iron residues in the spent acid from titanium dioxide manufacture may be removed by crystallization of first FeS04 7FI2O followed by crops of various iron(II) salts, or by electrodialysis [67]. Incidentally electrodialysis has also been used for sulfuric acid recovery from wastewater, either directly or after preconcentration on cation exchange resin [68]. 

Together, the annual output of the 2 factories is over 700 tonnes of cadmium metal of a purity of 99.99 % by weight and more than 650 tonnes of nickel in the form of iron nickel residues (1,900 tonnes) or ferro-nickel. The balance is made of plastic materials (cases of the industrial batteries, plastic shells around the power packs etc.), of scrap iron (metallic cases of the industrial batteries, iron residues coming form the distillation of negative pocket plates). These products are valorised at a market value either for energy production or scrap. 

In both cases, the common points were a pressure, weight ratios (water/wood) near 4.5, amounts of iron ik % on dry wood). The products soluble in dichloromethane were called oils, those only soluble in acetone, not fluid at room temperature, were named tars. The solid residue consisted of insoluble compounds char and iron residue. The gases evolved during the reaction were mainly carbon dioxide (at least 90 %) and carbon monoxide. The aqueous phase also contained organic compounds, in about 8 % yield in a slow liquefaction at 340 C, consisting mainly of carboxylic acids and alcohols, but they were not studied further. 

Alternatively, the intermediate formation of iron metal clusters can be avoided using a ligand exchange of CO for DCB by heating occluded iron carbonyl between 343 and 473 K in presence of DCB. As the starting NaY zeolite contains 3 Fe(C0)5 molecules per supercage (33), iron residues remain always in... 

Optimization starts with determining the zinc concentrate mix to be treated. This determination must be made considering all recoverable metal values and also the downstream metallurgical and operational constraints in the rest of the zinc and lead operations. Zinc concentrates with greater precious metal values typically also contain more iron and other impurities, resulting in a lower zinc metal production and an increased production of iron residues, whieh reduces available smelter capacity for other feed materials. Thus the optimum zinc concentrate feed mixture is based on all final products produced considering all downstream capacity implications. 

A pyrometallurgical process for the direct recovery of zinc from zinc concentrates and zinc/iron residues has been proposed and tested extensively by Noranda. The process consists of smelting bone-dry zinc containing materials (sulfide concentrates and secondary zinc/iron materials) in a molten iron oxysulfide bath to volatilize metallic zinc into a SOz-fiee ofTgas. Sulfiir contained in the feed materials is fixed as an iron oxysulfide matte for di sal. Thus, this process not only is capable of treating zinc sulfide concentrates and secondary zinc materials simultaneously, but also eliminates the need of sulfuric acid production. Detailed thermodynamic analysis and experimental test work are described in this paper. 

---