Microstructure characterisation of freeze linings formed in a copper slag cleaning slag

Jansson, J.; Taskinen, Pekka; Kaskiala, M.

doi:10.2298/jmmb130320004j

Cited by 6 publications

(3 citation statements)

References 10 publications

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“…In developed countries strict regulations already force large nickel and copper producers to employ separate cleaning processes for slags with high heavy metals content. Therefore, with the goal to achieve less than one percent of heavy metals in disposed slags with lower process disruptions [19] a better understanding of thermodynamic and kinetic parameters of settling process should be done and research on the development of new additives (reductants and/or fluxes) [20,21].…”

Section: Discussionmentioning

confidence: 99%

Nickel, copper and cobalt coalescence in copper cliff converter slag

Wolf

Mitrašinović

2016

J min metall B Metall

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The aim of this investigation is to assess the effect of various additives on coalescence of nickel, copper and cobalt from slags generated during nickel extraction. The analyzed fluxes were silica and lime while examined reductants were pig iron, ferrosilicon and copper-silicon compound. Slag was settled at the different holding temperatures for various times in conditions that simulated the industrial environment. The newly formed matte and slag were characterized by their chemical composition and morphology. Silica flux generated higher partition coefficients for nickel and copper than the addition of lime. Additives used as reducing agents had higher valuable metal recovery rates and corresponding partition coefficients than fluxes. Microstructural studies showed that slag formed after adding reductants consisted of primarily fayalite, with some minute traces of magnetite as the secondary phase. Addition of 5 wt% of pig iron, ferrosilicon and copper-silicon alloys favored the formation of a metallized matte which increased Cu, Ni and Co recoveries. Addition of copper-silicon alloys with low silicon content was efficient in copper recovery but coalescence of the other metals was low. Slag treated with the ferrosilicon facilitated the highest cobalt recovery while copper-silicon alloys with silicon content above 10 wt% resulted in high coalescence of nickel and copper, 87 % and 72 % respectively.

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Section: Discussionmentioning

confidence: 99%

Nickel, copper and cobalt coalescence in copper cliff converter slag

Wolf

Mitrašinović

2016

J min metall B Metall

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“…The spherical bottom of the cold finger and its heat flux were neglected in the model calculations. The thermal conductivity of the freeze lining was estimated in an earlier study as 6.0 W m 21 K 21 (Jansson et al, 2013). Properties of a molten metal (Bi) were used to mimic the high copper DtoB slag.…”

Section: Resultsmentioning

confidence: 99%

Freeze lining formation on water cooled refractory wall

Kalliala

Kaskiala

Suortti

et al. 2015

Mineral Processing and Extractive Metallurgy

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The experimental study was focused into effects of a ceramic refractory lining, covering a metallic cooling element, as well as to properties and microstructures of the freeze lining formed in such cases in copper smelting and converting slags. The modified heat transfer pattern, due to the ceramic refractory lining and its air gap(s), increases effectively the average freeze lining temperature, heating its cold face from 30 to 50°C of the direct contact close to 800–900°C, even with refractory thicknesses of a few millimetres. This general feature has direct consequences to the microstructure and thickness of the freeze lining and probably also to its growth rate. The observations about effects of high copper iron silicate slag on the chemical corrosion of direct bonded magnesia–chromia refractories suggest that copper oxides are not the most aggressive components of direct to blister smelting slags. Impregnation of the fluid direct to blister slag into the open porosity of the brick, even on the cooled furnace wall, extends quickly in the initial contact several hundred micrometres into the refractory.

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“…The majority of these studies have focused on the phase assemblages and microstructures formed during the growth of the deposits. [43][44][45][46][47][48][49][50][51][52][53][54][55][56][57][58] EXPERIMENTAL RESULTS…”

Section: Modelsmentioning

confidence: 99%

Understanding Slag Freeze Linings

Fallah-Mehrjardi

Hayes

Jak

2014

JOM

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Slag freeze linings, the formation of protective deposit layers on the inner walls of furnaces and reactors, are increasingly used in industrial pyrometallurgical processes to ensure that furnace integrity is maintained in these aggressive, high-temperature environments. Most previous studies of freezelinings have analyzed the formation of slag deposits based solely on heat transfer considerations. These thermal models have assumed that the interface between the stationary frozen layer and the agitated molten bath at steady-state deposit thickness consists of the primary phase, which stays in contact with the bulk liquid at the liquidus temperature. Recent experimental studies, however, have clearly demonstrated that the temperature of the deposit/liquid bath interface can be lower than the liquidus temperature of the bulk liquid. A conceptual framework has been proposed to explain the observations and the factors influencing the microstructure and the temperature of the interface at steady-state conditions. The observations are consistent with a dynamic steady state that is a balance between (I) the rate of nucleation and growth of solids on detached crystals in a subliquidus layer as this fluid material moves toward the stagnant deposit interface and (II) the dissolution of these detached crystals as they are transported away from the interface by turbulent eddies. It is argued that the assumption that the interface temperature is the liquidus of the bulk material represents only a limiting condition, and that the interface temperature can be between T liquidus and T solidus depending on the process conditions and bath chemistry. These findings have implications for the modeling approach and boundary conditions required to accurately describe these systems. They also indicate the opportunity to integrate considerations of heat and mass flows with the selection of melt chemistries in the design of future high temperature industrial reactors.

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Microstructure characterisation of freeze linings formed in a copper slag cleaning slag

Cited by 6 publications

References 10 publications

Nickel, copper and cobalt coalescence in copper cliff converter slag

Nickel, copper and cobalt coalescence in copper cliff converter slag

Freeze lining formation on water cooled refractory wall

Understanding Slag Freeze Linings

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