METHOD FOR CRYOLITE RATIO DETERMINATION FOR ELECTROLYTE WITH CALCIUM, MAGNESIUM AND POTASSIUM FLUORIDES ADDITIVES USING XRF METHOD Russian patent published in 2017 - IPC C25C3/06 

FIELD: chemistry.

SUBSTANCE: invention relates to a method for determination of the cryolite ratio (CO) of molar ratio (NaF+KF)/AlF₃) with added potassium, magnesium and calcium fluorides. The method includes plotting of calibration curves for Na, F, Ca, Mg, using industry standard samples (ISS) of electrolyte composition for aluminum production electrolysers, that have passed metrological certification, and for K - with synthetic electrolyte samples with established procedure of preparation with potassium content error values in the form of regression. Calibration characteristics for fluorine, sodium, calcium, and magnesium are plotted as a regression dependence: C_i=(b, I, +c_i)(1+M)i-Σ-p_iC_i, j≠k≠I, where i is the defined element, j is the element involved in absorption (imposition) of the defined element, k is the element involved in excitation of the defined element, b_i, c_i are coefficients of the regression equation for the i-th element, determined by the least square method, s/imp., wt %, respectively, I_i is the measured intensity of i-th element fluorescent emission, imp./s, C_i is concentration of the i-th potassium, wt %, C_j is concentration of the j-th element of the matrix, wt %, P_j is the intensity overlap correction coefficient, p_j=0÷1; (1+M)_i is the matrix effect coefficient, the value of which is determined by the formula: where i is the defined element, α_j is the absorption coefficient, which is calculated by the least square method (wt %)^-1; β_k is the excitation coefficient, which is calculated by the least square method; _Ck is the concentration of the k-th element of the matrix, wt %; N is the number of elements, and potassium calibration characteristic is plotted as a regression dependence: C=aI²+bI+c, where: a, b, c are regression equation coefficients for potassium, determined by the least square method (s/imp.)², s/imp., wt %, respectively; I is the measured intensity of analytical potassium line fluorescence, imp./s; C is potassium concentration, wt %. Calibration characteristic for Na determination is plotted with α and β correction by Al, and calibration characteristic for F determination is plotted considering Na imposing and β correction by Al.

EFFECT: achievement of accuracy in СO determination in the electrolyte with addition of K.

2 cl, 5 dwg, 1 tbl