Influence of addition of calcium salts on extraction of potassium from phosphorus- potassium associated mineral

Abstract

In this article, calcium salts were added into the hydrofluoric acid-sulfuric acid (HF-H₂SO₄) leaching system, and their effects on the extraction of potassium from phosphorus-potassium associated mineral (mineral deposits containing Ca₅(PO₄)₃F (fluorapatite) and KAlSi₃O₈ (potassium feldspar)) were investigated. KAlSi₃O₈ was converted into water-soluble potassium fertilizers, and important factors affecting the extraction, including dosages of H₂SO₄, types and dosages of calcium salts were studied. The results showed that the maximum extraction of 75.3 wt.% was obtained with H₂SO₄ (70 wt.%) dosage of 5 mL. When the reaction was added with 0.15 g CaSO₄, the extraction rate of K of 95 wt.% was achieved, which was an increase by 19.7 wt.% compared with that without calcium salts. Moreover, the Eh-pH diagrams for K-Si-(P)-(F)-(Ca)-H₂O systems were plotted and applied to analyze the mechanism of potassium extraction in the HF-H₂SO₄ reaction system. The analysis demonstrated that with the presence of F^-, the formation of fluoro-complexes enlarged the stable regions of soluble phosphorus (KPF₆) and silicon (K₂SiF₆). However, when calcium salts were added, such region decreased with the increase of [Ca² ⁺]; and such trends suggested that [K⁺] could be enhanced by adding [Ca² ⁺] during the leaching process.

Keywords

Phosphorus-potassium associated mineral calcium salts potassium extraction dissolution

Get full access to this article

View all access options for this article.

References

Liu

J.X.

, Analysis of Domestic Phosphate rock resources,their exploitation and utilization, J Chemical Fertilizer Industry 6 (2009), 27–31.

Liu

Y.W.

, Qin

Y.H.

, Wang

C.W.

, et al., Study on Process Mineralogy for Phosphate Potassium Ore in Zhongjianping, Yichang, J Multipurpose Utilization of Mineral Resources 2 (2014), 69–71.

H.W.

, Su

S.Q.

, Liu

, et al., Potassium resource and sustainable development of potash salt industry in China, J Earth Science Frontiers 17 (2010), 294–310.

Shang

P.Q.

, Xiong

X.X.

and Li

B.Y.

, Discussion on the main potash-concentrated districts and the resource potential in China, J Geology of Chemical Minerals 33 (2011), 1–8.

Han

X.Z.

and Hu

, Research on the extract ion potassium from potash feldspar in the acid environment, J Industrial Minerals and Processing 9 (2005), 1–3.

Han

X.Z.

, Yan

and Hu

, Research on the reaction mechanism of potash feldspar and phosphate rock in the phosphoric acid, J Phosphate and Compound Fertilizer 22 (2007), 19–22.

Han

X.Z.

, Yao

W.T.

, Hu

, et al., Extraction of potassium from potash feldspar by ion-exchange, J Chinese Journal of Applied Chemistry 20 (2003), 373–375.

, Han

X.Z.

and Xiao

Z.H.

, Distribution of potash feldspar resources in China and its exploitation, J Geology of Chemical Minerals 3 (2005), 26–32.

Xie

Z.N.

, Shu

, Yao

Y.Y.

, et al., Study on decomposition potassium shale and by activated roasting, J Chemical Research and Application 6 (2016), 875–879.

10.

Liu

, Zhang

X.X.

and Pang

S.H.

, Study on preparation of potassium-calcium fertilizer from dolomite and potash feldspar, J Phosphate & Compound Fertilizer 11 (2015), 9–10.

11.

T.X.

and Yu

J.G.

, Experimental Study on Decomposition of K-feldspar with CaCl2 and NaCl for Extraction of Potassium, J The Chinese Journal of Process Engineering 11 (2017), 1686–1691.

12.

Wei

M.X.

and Wang

G.L.

, Process of extracting potassium feldspar, J Industrial Minerals and Processing 39 (2010), 22–29.

13.

Xue

Y.H.

, Zhou

G.Z.

and Zhang

G.Z.

, The Potassium-Feldspar-Fluorite-Sulfuric acid system inside to resolve the studying of the potassium-feldspar, J Chemistry and Bioengineering 21 (2004), 25–27.

14.

Physical

X.C.F.

and Beijing:

Chemistry.

, Higher Education Press; 1998.

15.

Longhui

, Lisheng

and Zuomi

, Experimental study on kinetics of thermal decomposition process of potash feldspar gypsum calcium carbonate, J Journal of Chemical Engineering 14(3) (2000), 258–263.

16.

Man

, Lin

and Dingsheng

, Production of compound fertilizer by thermal decomposition of potassium feldspar -CaSO4-CaCO3 system, J Chemical Fertilizer Industry 37(2) (2010), 29–32.

17.

Birong

and Lin

, Analysis of thermal decomposition process of potassium feldspar - calcium sulfate - calcium carbonate system, J Chemical Minerals and Processing (3) (2011), 12–15.

18.

Liang

, Shaomin

, min

, et al., Effect of negative pressure on the dissolution behavior and mechanism from potassium feldspar, J Main Group Chemistry 16 (2017), 275–289.

19.

J.S.

, Lei

X.R.

and Zhang

J.H.

, Mineral X-ray powder crystal identification manual: Huazhong University of Science and Technology Press;, 2001.

20.

Lin

, Liu

G.H.

, Zhang

H.M.

, et al., Improvement of determination for the content of potassium and sodium in food by flame atomic emission spectrometry, J Journal of Applied Preventive Medicine 6 (2015), 391–395.

21.

Gacm

S.G.S.

, Wet chemical etching of silicate glasses in hydrofluoric acid based solutions, J Mater Sci 28 (1993), 6261–6273.

22.

Gacm

S.G.S.

and Van Dij

K.J.

, The dissolution of Na2O-MgO-CaO -SiO2 glass in aqueous HF solutions, J Mater Sci 22 (1987), 1869–1874.

23.

Stefansson

, Dissolution of primary minerals of basalt in natural waters I. Calculation of mineral solubilities from 0 °C to 350 °C, J Chemical Geology 172 (2010), 225–250.

24.

Verhaverbeke

, T

and V

, The etching mechanisms of SiO2 in hydrofluoric acid, J ElectrochemSoc 141 (1994), 2852–2857.

25.

Yuan

, Li

, Liang

, et al., Extraction of potassium from K-feldspar via the CaCl2 calcination route, J Chinese Journal of Chemical Engineering 9 (2015), 1557–1564.

26.

Lund

and Fogler

H.S.

, Acidization-II The dissolution of calcite in hydrochloric acid, J Chemical Engineering Science 30 (1975), 825–835.

27.

Stefansson

, Gıslason

S.R.

and Arnorsson

, Dissolution of primary minerals in natural waters II. Mineral saturation state, J Chemical Geology 172 (2001), 251–276.

28.

G.J.

and K

L.C.

, Metal removal from silicon surfaces in wet chemical systems, J Electron Mater 24 (1995), 397–404.

29.

Fogler

H.S.

and Lund

, Acidization-III The Kinetics of the dissolution of sodium and potassium feldspar in HF/HCl acid mixtures, J Chemical Engineering Science 30 (1975), 1325–1332.

30.

Hekim

and Fogler

H.S.

, Acidization-III On the equilibrium relationships and stoichiometry of reactions in mud acid, J Chemical Engineering Science 32 (1977), 1–9.

31.

O-A

, W

and M

K.K.

, Dissolution windows for wet chemical processing of silicon and silicon dioxide: potential-pH diagrams for the Si-F-H2O system, J Electrochem Soc 143 (1996), 749–751.

32.

, F

M.O.

, Q

A.M.

, et al., Acid leaching of alloys within the quaternary system Fe-Si-Ca-Al, J Industrial & Engineering Chemistry Research 36 (1997), 5291–5295.