Fluorite is a main source of hydrogen fluoride [6]; it is commonly used for the production of wide range of materials. HF is evaluated from mineral by the reaction with concentrated sulfuric acid.

CaF₂(s) + H₂SO₄ → CaSO₄(s) + 2 HF (g)

The produced HF is converted into fluoride, fluorocarbons and produced different materials. In 1990s annually production of CaF₂ is five billion kilogram. There are three main type of natural fluorspar used in industries. Metallurgical grade fluorite (60-85% CaF₂), Ceramic grade fluorite (85-95% CaF₂) and highest grade, “acid grade fluorite” (97% or more CaF₂), accounts for about 95%.

Metallurgical grade has been used traditional as flux; ceramic grade is used in the manufacturing of glass, enamels and cooking utensils. Acid grade used to make hydrogen fluoride and hydrofluoric acid and traditionally by reaction with fluorite with H₂SO₄ [7,8].

ESTIMATION OF FLUORSPAR BY DIFFERENT SCIENTIST

Calcium fluoride contents were determined by EDTA in iron tailings. The samples were prepared by diluted acetic acid to leach calcium carbonate. The contents of CaF₂ consist of two parts one fluoride contents were illustrated by zirconium xylenol orange by spectrometer after CaF₂ was filtered according to these values concentration of CaF₂ were calculated and other practice of CaF₂ by leaching as precipitating with leaching aluminum chloride solution for titration calcium indicator used as indicator EDTA standard titration solution was used to determine for precipitation of CaF₂ in KOH medium. Therefore CaF₂ contents were calculated by values. This illustrated method was simple, rapid, précised and recovery could meet the requirements in the CaF₂ determination the standard deviation was less than 1% and recovery 99-101% [9].

The invented method is for the quantitative determination of calcium fluoride by EDTA titration. Take 0.2-0.50 g sample material into beaker then added HCl and boric acid solution heat and dissolved for 20-40 min filter sample and collecting filtrate wash precipitates present beaker cool and added water. If barium is present in sample <0.2 wt%, it is precipitating out taking out 10-20% filtrate in beaker with 80-100 ml water and used triethanolamine with KOH to maintained pH grater then 13 and titrate with EDTA standard solution in the presence of mixed indicator. In case of barium grater then >0.2 wt%, aliquot 10-20% of filtrate in beaker adding 40-50 ml introduce 2-5 drops sulfuric acid and boil 10-20 min and hold grater then 8 h and collect filtrate in another beaker washing the original beaker ppt and maintained filtrate volume 80-120 ml and add tri-ethanolamine maintained pH by using KOH gratering grater then 13, titrate with EDTA with mixed indicator.

In first step weight 0.20-0.30 g and 0.40-1.20 g samples material in two beakers then add HCl-H₂SO₄ solution hold at room temperature for 40-60 min and shake 3-50 min till ppt fully dispersed, 1-3 drop phenolphaline indicator and adding KOH the reddish color this process continue till HCL reddish color disappears, transfer solution in volumetric flask and fill with water and hold for 8 h then pipette out 30-50% and repeat same procedure after end of titration calculate non calcium fluoride calcium content in sample by using two volume difference and weight difference of sample materials. The mixed indicter is mixture of calcium, European Pharmacopoeia Reagent and potassium chloride. The invented method has precise and CaF₂ calculated values are authentication.

Fluorite powder directly analyzed by XRF after pressed pellet combination with spectroscopy, the total content of Ca and content of Fe₂O₃, P, SiO₂ and K₂O as well as carbon present in sample analyzed by IR absorption spectrometer and carbon content calculated as CaCO₃ then CaF₂ calculated content in fluorite. For estimation of unknown samples the working curve was made using nine certified reference material the method is accurate and further verification an accuracy standard (GBW07254) was used to test accuracy and precision of method and found results satisfactory [10].

Analysis of fluorspar by traditional method after separating calcium carbonate and calcium fluoride it takes longer time and not suitable for production but accuracy of results from this method is very high. The publisher was illustrated two methods, alkali fusion and acid leaching method. The operation analyzing results of this method was very easy and short time for completion of analysis and observed that results were accurate and it could be used for quick analyzing before production.

The fluorite standards prepared in group and samples with binder formed in the form of pressed pellets method. These press pellets analyzed by x-ray fluorescence spectrometer and obtained liner regression line. Curves after deduction of enhanced absorption and spectral line overlap interference determine the content of pressed pellet by using curve and calculate the fluorite by analysis of the corresponding relation of spectral line intensity and concentration. The standards samples and binder after sieving 300 mesh formed press pellet by using palletizer. This creative method is rapid and accurate and can reduce the estimation cost and enhance the detection limits. [11].

Other method for estimation of calcium fluorite as CaC₂ with diluted acetic acid. CaF₂ cannot dissolved in acetic acid therefore sample was treated with acetic acid and insoluble material filtered by filter paper then introduced potash solution till pH attain 13 or greater than 13. CaC₂ was determined by EDTA titration method. Insoluble filtered material and filter paper was burned in platinum crucible and added mixed flux with boric acid melt at 950°C than acidify and added potash solution till pH 13 or greater and analyze CaF₂ with EDTA titration. The RSD value of CaC₂ was 0.064 and 0.01916% and CaF₂ RSD value observed 0.6285 and 0.8357%.

Fluorspar contents like CaF₂, SiO₂, Al₂O₃ and total iron (TFe) are calculated by XRFS. The samples were prepared by 1 g of sample and fusion mixture KNO₃ (0.2 g), Li₂CO₃ (1.0 g) and Li₂B₄O₇ (5.0 g) in a Pt crucible and after addition of 3 drops of 150 g/L^-1 LiBr solution, the mixture was fused at 1050° for 20 min. after cooling the 4 components were estimated. Samples present with reductive substance the fusion method should be modified. Li₂B₄O₇ put in the platinum crucible after melting coated on inner wall of crucible at lower and bottom side. After cooling, KNO₃ and Li₂CO₃ added to the crucible and peroxide at low temperature and fused sample as same procedure. The melt sample was used for detection of 4 components. Working curve prepared and used for estimation of results. Four samples were analyzed by said method and giving results has consistency with results [12].

Review on new published paper “Quantification of Metallurgical Flux by Wavelength Dispersive X-ray Fluorescence” this advance test method was developed for the quantification of fluorspar (CaF₂) along with other present ingredients especially trace elements like Ba, Sr, P and Mg. All above reported abstract showed that few methods are invented in which analysis of fluorspar has carried out partially and did not emphasize on complete chemistry of fluorspar. It can only analyze Si, P, K, Na and other elements Ca soluble and total were analyzed by classical methods.

The current established method can analyze necessary elements by WDXEF and carbon was analyzed by carbon sulphur analyzer as well as presence of CO₂ as CaCO₃ was confirmed by using ATR-FTIR and XRD method.

EXPERIMENTAL

Estimation of minerals XRF

WD-XRF- Philips Axios Max, 3KW Rhodium tube as X-ray generator along with crystals, channels and collimator mask was used for creation of application and analyze standards and unknown samples. Carbon was analyzed by CS-800 (Eltra) analyzer [12].

STANDARDS AND CALIBRATION

Initially calibration lines of SiO₂, Ca, P, SrO, BaO, Fe₂O₃ were developed in WDXRF with known chemical composition of primary standards as well as synthetic standards and same standards except synthetic standards were utilized for carbon development calibration line in CS-800 analyzer. The following primary standards were used for calibration of lines i- JK S9, ii- NCS DC 14023, iii- NCS DC 14025, iv- NCS DC 62003a, v- HJ-CGL 101, vi- UNS LAB Fluorite FM, vii- ICRM-5132-89, viii -JK S10, ix- BCS 392 as well as utilized high purity analytical reagents of silica (SiO₂), calcium oxide (CaO), calcium fluoride (CaF₂), aluminum oxide (Al₂O₃), magnesium oxide (MgO) and ferric oxide (Fe₂O₃) for synthetic standards (Table 1).

SAMPLES OCCURRENCE AND COMPOSITION

40 samples were collected by random sampling from different locations of Pakistan Jurassic Loralai limestone of Gadebar, Daman Ghar, tor Thana, Wategam, Mekhtar, Balao, Mahiwal areas of Loralai District. The fluorite of Loralai area occurs as veins and as disseminated grains along faults and fractures which is hosted by the Jurassic Loralai limestone forming the anticlinal core. Fluorite has many colors such as pink, blue, light-grey, green and light-yellow (Picture 2). Chemical analysis shows CaF₂ varies from 95.20-95.40%, CaCO₃ from 3.20-3.40% and SiO₂ from 1.40-1.44%. Average weight % concentration of Ca is 49%, F is 45%, SiO₂ is 2.30%, CuO is 0.5%, Al₂O₃ is 2%, Fe₂O₃ is 0.08% and LOI is 1.47%. This type of fluorite can be used for acid preparation and also as gemstones.

Homogeneity of samples through grinding method, grinding time, mesh size, pelletized force binder type and ratio. After said process samples passed through 150 µm and oven dry at 105°C for 24 h and observed lose 0.001-0.10%.