References of "Ionkov, Krassimir"
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See detailAmenability for processing of oolitic iron ore concentrate for phosphorus removal
Ionkov, Krassimir ULg; Gaydardzhiev, Stoyan ULg; Correa de Araujo, Armando et al

in Minerals Engineering (2013), 46-47

Beneficiation routes aimed at dephosphorisation of oolitic gravity magnetic concentrate and involving a combination of roasting, re-grinding, magnetic separation and water and acid leaching are ... [more ▼]

Beneficiation routes aimed at dephosphorisation of oolitic gravity magnetic concentrate and involving a combination of roasting, re-grinding, magnetic separation and water and acid leaching are investigated. Roasting was carried out at 900ºC for one hour without or with lime or sodium hydroxide as roasting additives. When additives were used, cement phases of Si-Al-Na-Ca-O type were detected as well as the mineral giuseppettite. During the thermal process sodium silicate is liquefied and the newly formed phases coat the oolites and penetrate inside the cracks. Energy Dispersive Spectroscopy analysis has indicated that the zone surrounding the oolites consists of Na, Al and Si phases with part of phosphorus being captured there. As a result of the alkaline roasting, goethite is partly transformed to magnetite and this reduction is reinforced with an increase in sodium hydroxide dosage. Investigation of redistribution of phosphorous shows that it could be only partly separated if leaching is not accompanied by re-grinding and physical separation. The recommended dosage of the reductive agent for the final flowsheet is 8 % mass ratio to concentrate. Grinding to a mean size of 0.040 mm, with water and acid leaching and double magnetic separation creates conditions to obtain a high-quality iron concentrate with 65.97 % Fe and recovery of 92.43 %, with simultaneous decrease in the phosphorus content from 0.71 % to 0.05 %. [less ▲]

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See detailPotential for application of alkali roast acid leach technology for removal of phosphorus from iron ore
Ionkov, Krassimir ULg; Gaydardzhiev, Stoyan ULg; Bastin, David ULg et al

in Proceedings of 6-th International Congress on the Science and Technology of Ironmaking ICSTI (2012, October)

The present study deals with the effect of sodium hydroxide and sodium carbonate used as additives during oxidizing roasting of oolitic limonite iron concentrate and more precisely upon the change in its ... [more ▼]

The present study deals with the effect of sodium hydroxide and sodium carbonate used as additives during oxidizing roasting of oolitic limonite iron concentrate and more precisely upon the change in its magnetic susceptibility. Further, the efficiency of Alkali Roast Acid Leach (ARAL) technology for dephosphorisation of the concentrate is compared with the case when sodium hydroxide was added in alkali leach after roasting. The treatment without additives in roasting resulted in obtaining iron concentrate with 58 % iron and 0.21 % phosphorus, while the ARAL approach yielded concentrate with 63 % iron and 0.09 % phosphorus. The influence of combination of coke as reducing agent and sodium hydroxide in roasting at 900°C is also investigated and results displayed in 3D form. The combination of ARAL with reductive roasting, grinding of the clinker to 80 % - 0,075 mm, flotation of the non-reacted coke and magnetic separation before and after the acid leach resulted in iron concentrate with 66 % iron and 0.05 % phosphorus. The study has shown that the application of the ARAL approach with low addition of alkalis followed by 10 to 15 minute acid leaching at ambient temperature could substantially reduce phosphorus, thus offering the possibility for efficient treatment of high phosphorus iron ores. [less ▲]

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See detailRemoval of phosphorous through roasting of oolitic iron ore with alkaline earth additives
Ionkov, Krassimir ULg; Gaydardzhiev, Stoyan ULg; Bastin, David ULg et al

in Proceedings of the XXVI International Mineral Processing Congress (2012, September)

The present study is devoted to improvement of the leaching efficiency during phosphorous removal from high phosphorous gravity-magnetic concentrate. Before leaching the concentrate has been subjected to ... [more ▼]

The present study is devoted to improvement of the leaching efficiency during phosphorous removal from high phosphorous gravity-magnetic concentrate. Before leaching the concentrate has been subjected to roasting with the addition of either Ca(OH)2 or CaO. The oolitic iron ore is roasted at 900°C for one hour. This reflects in reaction between alkaline earth additive and quartz, aluminosilicates, phosphorus, and some other minor components of the gangue minerals. The application of leaching, physical separation, and wash out of salts has resulted in the decrease of phosphorus from 0.7 to 0.15 % and it is established that the major influencing factor is the concentration of acid and to a less extent duration of the leaching process. About two third of the phosphorus can be removed by roasting with 3 % CaO to hematite, coarse grinding to d50 0.3 mm, dry high intensity magnetic separation and leaching of the magnetic fraction with hydro-chloric or nitric acid. [less ▲]

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See detailDEPHOSPHORIZATION OF LIMONITIC CONCENTRATE BY ROASTING, ACID LEACHING AND MAGNETIC SEPARATION
Ionkov, Krassimir ULg; Gaydardzhiev, Stoyan ULg; Corea de Araujo, Armando et al

in Holmes, M. (Ed.) Proceedings of the Iron Ore 2011 International Conference (2011, July)

The oolitic iron ore reserves in Lisakovsky, Northwest Kazakhstan represent a quite challenging deposit both from technological and from resource point of view. The difficulties in processing such type of ... [more ▼]

The oolitic iron ore reserves in Lisakovsky, Northwest Kazakhstan represent a quite challenging deposit both from technological and from resource point of view. The difficulties in processing such type of ore are connected with the extremely fine dissemination of phosphorus and gangue minerals inside the oolitic formations. The goethite crystals are cemented in their structure by aluminosilicates with quartz and other gangue minerals and dissemination is so fine that they are not separable by physical methods. The laboratory tests performed in direction of dephosphorisation have shown that the combination of alkaline roasting followed by low intensity magnetic separation and acid leaching enables the obtaining of high grade iron concentrate. The magnetic separation performed ahead of leaching has been efficient by means of buffering the high pH via washing out the soluble salts and the excess of bases and applied after leaching has facilitated the removal of secondary liberated gangue minerals in the non-magnetic fraction. As a consequence, phosphorous content has been dropped to a more acceptable for the ferrous metallurgy levels while iron grade and recovery have reached respectively 61.6 and 80.8 percent. [less ▲]

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