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Enrichment, Separation, and Recovery of Phosphorus from Dephosphorization Slag

Yan-Ling Z., Ming G., Feng-Shan L., Kan Y.

Archives of Metallurgy and Materials

2018

Vol. 63, iss. 4

1769--1783

A better understanding of phosphorus distribution in slag is necessary to develop an effective way to treat dephosphorization slag formed during steelmaking. Here, previous studies on the enrichment, separation, and recovery of phosphorus from dephosphorization slag are reviewed, along with their influencing factors. The results suggest that a proper heat treatment can promote the selective enrichment and growth of P-rich phases. Further, adding P2O5 and FetO facilitates phosphorus enrichment. Also, Ca3(PO4)2 is precipitated from slag containing 18 wt% P2O5. MnO and MgO in the slag barely affect the phosphorus recovery. In contrast, the addition of Al2O3 and TiO2 significantly affects phosphorus enrichment and magnetic separation. A phosphorus recovery rate of more than 70% is achieved with the addition of 10 wt% Al2O3 or 10 wt% TiO2. New phases (Na2Ca4(PO4)2SiO4, Na3PO4, and Ca5(PO4)3F) tend to be formed on the addition of Na2O and CaF2, which promote phosphorus enrichment. However, the addition of Na2O and CaF2 results in the incomplete separation of phosphorus and iron, as CaF2 and Na2O improve slag metallization and the magnetism of iron-rich phases.

Anthropogenic changes in properties of the water and spatial structure of the vegetation of the lobelia lake Lake Modre in the Bytów Lakeland

Kraska M., Klimaszyk P., Piotrowicz R.

Oceanological and Hydrobiological Studies

2013

Vol. 42, No. 3

302--313

Lake Modre is a lobelia lake. Numerous typical plant species occur here, including Lobelia dortmanna, Littorella uniflora, Isoetes lacustris, and Sphagnum denticulatum. They develop the following associations: Lobelietum dortmannae (Oswald 1923) Tx. ap. Dierss. 1972, Isoetetum lacustris Szańkowski et Kłosowski 1996 n.n., and a community with Sphagnum denticulatum Brid. In 1991, the water of the lake was characterised by low concentrations of nutrients and calcium, acid reaction (pH<5), and Secchi depth visibility of 12 m. Following fry stocking in the lake in 1993 fish farming took place until approximately 1996. During this period the water quality in the lake changed radically in physiochemical terms. Water transparency decreased. Thermal and oxygen stratification developed, with oxygen deficits in the near-bottom layer. Concentrations of nutrient elements increased. Drastic long-term changes were observed in the spatial and quantitative features of the lake vegetation. These particularly related to the instability of Lobelia dortmanna, and the diminishment of the phytocoenosis of Lobelietum dortmannae. Consequently, the phytocoenosis occurred only in the shallowest part of the phytolittoral. L. uniflora expanded, increasing its occurrence annually. Significant fluctuations in quantities of S. denticulatum occurred, correlated with changes in physiochemical water parameters, but shifted in time.