A study of possibility of decline of maintenance of zinc is in metallurgical liquid wastes

Author : Gorlova O.
Sourse: Minerals and Metallurgical Processing Journal. - №2 - 2005 - p.20-24.

        Liquid wastes are the second technogenic raw material. Dehydrated liquid wastes and caught dusts of all metallurgical productions is used mainly as additions in an aggloburden and are replacement to part of primary ore raw material. Expansion of source of raw materials due to the use of the second raw material is actual and for the Magnitogorskogo metallurgical combine
        Current output of blast-furnace and sinterings liquid wastes OAO «MMK» makes 400 thousands of tons with the mass stake of iron in liquid wastes on the average 51,6 %. In addition, the far of liquid wastes is accumulated in depository of liquid wastes. For dehydration of current liquid wastes of equipment for cleaning of gas of high furnaces, martin workshops and liquid wastes of agglofactories.
        On setting condensing of containing liquid wastes waters, dehydration and drying of liquid wastes which after return on utilization in the charge of agglofactory is carried out.
        Economic efficiency of the use of the second raw material in a metallurgical production to a great extent depends on quality of slime products, which in same queue is determined by not only maintenance of useful components (iron, manganese, oxide of calcium and pr.) but also presence of harmful admixtures (zinc, lead, sulphur, alkaline metals).
        A basic problem during utilization of metallurgical liquid wastes is enhanceable maintenance in them of zinc, especially in connection with expansion of the use of zincked skrapa in a converter production. Utilization of these liquid wastes in agglofactory without preliminary dezincification causes destruction of laying of high furnaces, hammering in the aspiration systems.
        It substantially influences to work of high furnaces and sintermachines, the same diminishing the TBO periods of high furnaces and expensive aspiration systems. The most difficult chemical composition is had liquid wastes of equipment for cleaning of gas of blast-furnace and steelmaking production.
        These liquid wastes in the process of education is exposed to high temperature influence in the conditions of oxidizing or restoration atmosphere. There is formation of ferrits of zinc at chemical co-operation of oxides of zinc and iron. In liquid wastes zinc is present also as free grains of oxide of zinc – mineral of zincite.
        Above the problem of cleaning of ferriferous dusts from zinc, their utilizations work in many countries of the world. The most offered methods of dezincification of metallurgical liquid wastes can be grouped as follows: pyrometallurgical, gidrometallurgicheskie, gravity. In industrial scales in many countries of the world the pyrometallurgical processes of utilization of ferriferous dusts and liquid wastes will be realized by their making of preforms with subsequent metallization of okuskovannogo material in the revolved stoves.
        In these processes simultaneously with renewal of oxide of iron in stoves at high temperatures greater part of zinc is sublimated as steams, lead, alkaline metals, steam is usually caught in electric filters, utilized and head for the enterprises of the coloured metallurgy. Technological indexes in these processes are high enough, but building of the special expensive settings is required. In this work the attempt of decline of maintenance of zinc is done in metallurgical liquid wastes with the use of concentrating processes – magnetic division and reverse flotacii. The test of ferriferous liquid wastes, actings on the vacuum filter setting of OAO was selected for this purpose «MMK». Grain-size distribution of liquid wastes, magnetic descriptions of liquid wastes (specific magnetic receptivity, magnetized, coercitivity), hygroscopicity is certain in laboratory terms. The study of distributing of zinc rotined on the classes of largeness, that zinc was mainly concentrated in factions –0,25 +0,18 mm and are 0,04 mm; a dezincification in these factions is 22,7 and 25,9 % accordingly. Mass stake of zinc in a test from data of chemical analysis 2,08 %.
        One of effective methods of enriching of thin classes magnetic and weak magnetic properties of ores is poligradientnaya separaciya. Poligradientnye separators, based on filtration of mash through the layer of by volume ferromagnetic environment, allow considerably to increase tension and gradient of the magnetic field, surface which a division is on, decrease the relative rate of movement of particles, and, consequently, and largeness of the enriched material. Tested on a laboratory separator, consisting of electromagnetic staple, between the poles of which a cassette, filled by metallic marbles, actings part magnetic attachments, is placed. Magnetic field into a working area heterogeneous on tension and on magnetic force. As a result on the particles of liquid wastes at passing them in the running mode in a gap magnetic force, changing in wide limits, operates between balls. Shlamy, possessing high magnetic receptivity, is attracted in areas with the high gradient of the magnetic field to the balls, and weak magnetic properties particles speed away water in tails. In weak magnetic properties part must pass the oxide of zinc, the same reducing the mass stake of zinc in magnetic faction. The indexes of division of liquid wastes materials on poligradientnykh separators are largely determined by correctly neat parameters. Carried out tests at varying of current of magnetizing of spools of excitation, closeness of feed, diameter of balls, height of layer of balls. Influence was studied each of the transferred parameters on the indexes of division, but considerable decline of maintenance of zinc in magnetic faction, getting was not succeeded. At the set optimum parameters of process (current of magnetizing 1 And, expense of washwater 300 ml, maintenance hard in a feed 7 %, the diameter of balls 9 mm, height of layer of balls 10 see) the maximal decline of mass stake of zinc was got in liquid wastes with 2,08 % (initial liquid wastes) to 1,83 % (magnetic faction При этом массовая доля цинка в немагнитной фракции равна 3,4 %, то есть наблюдается некоторая концентрация цинка в хвостах. Так как выход немагнитной фракции во всех опытах был небольшим и не превышал 15 % от исходной навески, извлечение цинка в немагнитную фракцию составляло 20 – 25 %. The got results testify that in magnitogorskikh liquid wastes there is a negligible quantity of zinc as a zincite, and a bulk of elementary zinc is on the ferrits of zinc. It is confirmed by information of complete mineral composition of liquid wastes in obedience to which on the stake of zinc in form zincite is only 7,3 %, and other 92,7 % zinc – on ferrits
        The ferrit of zinc possesses weak magnetic properties properties, therefore in the intensive magnetic field the ferrits of zinc stay too long in interpolar space and get in magnetic faction. Taking into account the similar specific of magnitogorskikh liquid wastes efficiency of poligradientnoy separacii of liquid wastes appeared practically zero. Herein there is a positive side. Impossibility of dezincification of these liquid wastes is experimentally rotined magnetic separaciey. As zinc in liquid wastes is presented mainly by ferrits, possibility of separation was studied them from liquid wastes flotaciey with the preliminary activating of connections of zinc by a blue vitriol. The series of flotacionnykh experiments are conducted in the mode of reverse flotacii on a next chart. In initial mash, warmed-up to 300 With, gave a blue vitriol and mixed during set time for activating of connections of zinc, whereupon subjected flotacii with the use of ksantogenata and matter, formative suds. Thus ferriferous minerals of depressirovali are in a environment with high maintenance of lye, by the created lime. The output of foamy product made from 5 to 9 % with the mass stake of zinc 4 – 5 %. A ferriferous concentrate was got a chamber product. The mass stake of zinc in him as compared to initial liquid wastes diminished from 2,23 to 1,9 %. Thus, at development of the optimum reagentik mode of reverse flotacii the considerable concentration of zinc can be got in a foamy product. Researches in this direction will be continued, because at a this method of division simultaneously the task of decline of zinc decides in a ferriferous product and a containing zinc product turns out additionally.