Leaching of Phosphorus from Quenched Steelmaking Slags with Different Composition

Separating P2O5 from steelmaking slag is the key to achieving optimum resource utilization of slag. If the P-concentrating 2CaO∙SiO2–3CaO∙P2O5 solid solution was effectively separated, it can be a potential phosphate resource and the remaining slag rich in Fe2O3 and CaO can be reutilized as a flux in steelmaking process. In this study, a low-cost method of selective leaching was adopted, and hydrochloric acid was selected as leaching agent. The dissolution behavior of quenched steelmaking slags with different composition in the acidic solution was investigated and the dissolution mechanism was clarified. It was found that the P dissolution ratio from each slag was higher than those of other elements, achieving an effective separation of P and Fe. The dissolution ratios of P, Ca, and Si decreased as the P2O5 content in slag increased. A higher Fe2O3 content in slag led to a lower P dissolution ratio. Increasing slag basicity facilitated the dissolution of P from slag. The residue mainly composed of matrix phase and the P2O5 content decreased significantly through selective leaching. The P dissolution ratio from slag was primarily determined by the P distribution ratio in the 2CaO∙SiO2–3CaO∙P2O5 solid solution and the precipitation of ferric phosphate in the leachate. The P-concentrating solid solution was effectively separated from quenched steelmaking slag, even though hydrochloric acid was used as leaching agent.

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Effect of Fe2O3 Content and Acid on the Leaching Behavior of Phosphorus from Dephosphorization Slag

Minerals ◽

10.3390/min11090972 ◽

2021 ◽

Vol 11 (9) ◽

pp. 972

Author(s):

Shi-Wei Liu ◽

Ping-Ping Li ◽

Chuan-Ming Du ◽

Ning-Ning Lv

Keyword(s):

Solid Solution ◽

Hydrochloric Acid ◽

Acid Solution ◽

Selective Leaching ◽

Leaching Behavior ◽

Fe2o3 Content ◽

P2o5 Content ◽

Dephosphorization Slag ◽

Dissolution Ratio ◽

Almost All

Dephosphorization slag contains considerable quantities of valuable components, such as P2O5 and FeOx. To recover P from dephosphorization slag, selective leaching has been adopted to separate the P-concentrating mineral phase. In this study, the effect of Fe2O3 content in slag and acid on the leaching behavior of P from dephosphorization slag was investigated. It was found that a higher Fe2O3 content in slag resulted in a higher P2O5 content in the C2S–C3P solid solution. Increasing the Fe2O3 content in slag promoted the dissolution of P and simultaneously suppressed the dissolution of other elements, facilitating the selective leaching of P. In the hydrochloric acid solution, more than 81% of P could be dissolved from dephosphorization slag at pH 4, and the dissolution ratio of Fe was nearly zero, achieving excellent selective leaching. Although better selective leaching was also realized in the citric acid solution at pH 5, hydrochloric acid was considered the appropriate leaching agent from the perspective of leaching cost. Through selective leaching, almost all the C2S–C3P solid solution was dissolved from dephosphorization slag, and the Fe-bearing matrix phase and magnesioferrite remained in the residue. The residue with low P2O5 content can be reutilized in ironmaking or steelmaking processes.

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Dissolution Behavior of Dicalcium Silicate and Tricalcium Phosphate Solid Solution and other Phases of Steelmaking Slag in an Aqueous Solution

High Temperature Materials and Processes ◽

10.1515/htmp-2012-0032 ◽

2012 ◽

Vol 31 (4-5) ◽

pp. 329-338 ◽

Cited By ~ 38

Author(s):

Takuya Teratoko ◽

Nobuhiro Maruoka ◽

Hiroyuki Shibata ◽

Shin-ya Kitamura

Keyword(s):

Solid Solution ◽

Aqueous Solution ◽

Tricalcium Phosphate ◽

Dicalcium Silicate ◽

Matrix Phase ◽

Dissolution Behavior ◽

Steelmaking Slag ◽

P Content ◽

The Matrix ◽

Dissolution Ratio

AbstractMost of the phosphorus in slag forms a solid solution of dicalcium silicate (C2S) and tricalcium phosphate (C3P), and the process used to separate this solid solution from the matrix phase is the same technology used to separate P from other valuable elements such as Mn and Cr containing in the matrix phase. Although it is known that the solubility of C2S in an aqueous solution is much greater than that of C3P, the solubility of the solid solution and that of the matrix phase have yet to be investigated. To clarify the possibility of selectively extracting P from slag through a leaching process, the dissolution behaviors of the solid solution at various compositions and that of the matrix phase were investigated. The following results were obtained: The dissolution ratio of Ca to the aqueous solution at pH = 7 was close to 1.0 in the case of pure C2S and decreased greatly with increasing C3P content. The dissolution ratio of P was about 0.1 and did not change relative to the C3P content. When the ratio of C3P in the solid solution was higher than 0.3, hydroxyapatite (HAP) formation was observed in the residue. The dissolution ratio of P increased for 30 min, and after reaching the maximum value, started to decrease owing to the precipitation of HAP. The dissolution ratio of each element from a glassy slag sample (matrix phase) was lower than that from the solid solution at every pH level.In this study, the possibility to extract a solid solution containing P without dissolving the matrix phase was found through the use of an aqueous solution at pH = 7, although the dissolution ratio of P was not sufficiently high.

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Dissolution mechanism of various elements from steelmaking slag into citric acid solution

Metallurgical Research & Technology ◽

10.1051/metal/2018125 ◽

2019 ◽

Vol 116 (3) ◽

pp. 321

Author(s):

Ningning Lv ◽

Chang Su ◽

Hui Kong ◽

Jinxing Yang ◽

Weiming Liu ◽

...

Keyword(s):

Citric Acid ◽

Acid Solution ◽

Mass Balance ◽

Dissolution Mechanism ◽

Steelmaking Slag ◽

Citric Acid Solution ◽

Initial Concentration ◽

Predominant Species ◽

Dissolution Ratio ◽

The Relationship

To recycle valuable elements from steelmaking slag, their dissolution mechanism into citric acid solution has been investigated. First, the relationship between dissolution ratio of each element and initial concentration of citric acid (ci) was studied. Then, the concentrations of each species in solution were calculated through mass balance. Based on these results, it can been seen that whenci = 0.00104 mol/L, Ca2+, CaCit−, MgCit−, FeH2PO42+and CaHPO4are the predominant species in solution, and Ca5(PO4)3(OH)(s) precipitate can form easily, which may suppress the dissolution of elements. Whenciincreases to 0.0104 mol/L, dissolution ratio of each element increases significantly, except for iron. And the predominant species correspondingly change to Ca2+, Mg2+, CaCit−, MgCit−, H2Cit−, H3Cit and FeH2PO42+.

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A Review of Multi-phase Slag Refining for Dephosphorization in the Steelmaking Process

Frontiers in Materials ◽

10.3389/fmats.2020.602522 ◽

2020 ◽

Vol 7 ◽

Author(s):

Wenhui Lin ◽

Shuqiang Jiao ◽

Kaixiao Zhou ◽

Jiankun Sun ◽

Xiaoming Feng ◽

...

Keyword(s):

Solid Solution ◽

Molten Slag ◽

Intelligent Manufacturing ◽

Dissolution Behavior ◽

Steelmaking Slag ◽

Steelmaking Process ◽

Slag Refining ◽

Liquid Phases ◽

Fine Control ◽

Multi Phase

Dephosphorization has always been a challenging task in the steelmaking process. In the traditional studies, CaO-based steelmaking slag was usually treated as a homogeneous liquid phase to analyze the dephosphorization equilibrium between molten slag and hot metal (slag/metal). In fact, the slag shows a coexisting state of both liquid and solid at steelmaking temperature. In recent years, multi-phase slag refining has been proposed and proved to be an efficient technique to improve the utilization of solid lime and the dephosphorization efficiency in steelmaking practices. The present review focuses on hot issues for the multi-phase slag refining, including the dissolution of solid lime to the molten slag, the formation of 2CaO·SiO2 and phosphorus-rich solid solution of 2CaO·SiO2-3CaO·P2O5, as well as the phosphorus distribution ratio between the solid and liquid phases in the multi-phase slag. In addition to the discussion on thermal and kinetic factors of dephosphorization, the necessity of further research is proposed on the dissolution behavior of phosphorus-rich solid solution and phosphorus redistribution in the slag of high temperature, high basicity and high FeO in the final stage of converter steelmaking. Then, a more applicable dynamic model of dephosphorization could be expected considering the equilibrium not only between molten slag and liquid metal but also among the phases of the multi-phase slag in steelmaking process. Furthermore, the modelling work is beneficial for the fine control of the BOF process and the development of intelligent manufacturing in steelmaking industry.

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Effect of Fe2+/T.Fe Ratio on the Dissolution Behavior of P from Steelmaking Slag with High P2O5 Content

Journal of Sustainable Metallurgy ◽

10.1007/s40831-018-0190-4 ◽

2018 ◽

Vol 4 (4) ◽

pp. 443-454 ◽

Cited By ~ 3

Author(s):

Chuan-ming Du ◽

Xu Gao ◽

Shigeru Ueda ◽

Shin-ya Kitamura

Keyword(s):

Dissolution Behavior ◽

Steelmaking Slag ◽

P2o5 Content

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Dissolution Behavior of Elements in Steelmaking Slag Into Seawater

Experimental Analysis of Nano and Engineering Materials and Structures ◽

10.1007/978-1-4020-6239-1_418 ◽

2007 ◽

pp. 841-842

Author(s):

Takahiro Miki ◽

Mitsutaka Hino

Keyword(s):

Dissolution Behavior ◽

Steelmaking Slag

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Dissolution Behavior of Nutrition Elements from Steelmaking Slag into Seawater

ISIJ International ◽

10.2355/isijinternational.44.753 ◽

2004 ◽

Vol 44 (4) ◽

pp. 753-761 ◽

Cited By ~ 50

Author(s):

Takayuki Futatsuka ◽

Kiyoteru Shitogiden ◽

Takahiro Miki ◽

Tetsuya Nagasaka ◽

Mitsutaka Hino

Keyword(s):

Dissolution Behavior ◽

Steelmaking Slag

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Separation and recovery of phosphorus from steelmaking slag via a selective leaching–chemical precipitation process

Hydrometallurgy ◽

10.1016/j.hydromet.2019.105109 ◽

2019 ◽

Vol 189 ◽

pp. 105109 ◽

Cited By ~ 3

Author(s):

Chuan-Ming Du ◽

Xu Gao ◽

Shigeru Ueda ◽

Shin-Ya Kitamura

Keyword(s):

Chemical Precipitation ◽

Precipitation Process ◽

Steelmaking Slag ◽

Selective Leaching

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Efficient Autoclaved Silicate Concretes with the Use of Steelmaking Slag

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.284.956 ◽

2018 ◽

Vol 284 ◽

pp. 956-962 ◽

Cited By ~ 1

Author(s):

Yu.L. Starostina ◽

O.A. Plotnikova

Keyword(s):

Calcium Silicate ◽

Control Sample ◽

Steelmaking Slag ◽

Dry Milling ◽

Disposal Area ◽

Twofold Increase ◽

Steelmaking Slags ◽

Calcium Silicate Hydrates ◽

Crystallization Degree ◽

Silicate Materials

The article presents the findings of the research concerning the usage of slowly cooled crystallized steelmaking slags, taken from slag disposal area, in the raw mix for autoclaved silicate materials. By means of dry milling and with the use of this slag the slag-containing binders of various compositions and basicity were prepared. The application of steelmaking slags in the raw mix allows intensifying the process of new formations synthesis and increasing the amount and crystallization degree of low-basic calcium silicate hydrates of the tobermorite group, which provides more than twofold increase of strength characteristics of the obtained materials as compared to the control sample.

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