Effect of hydrochloric acid on leaching behavior of calcareous phosphorites (original) (raw)
Related papers
A review of the beneficiation of calcareous phosphate ores using organic acid leaching
Hydrometallurgy, 2010
The beneficiation of phosphate ores containing carbonate gangue by conventional techniques such as physical separation methods or flotation is very difficult due to the similarities in physico-chemical properties of constituent minerals present in the system. Carbonate-rich phosphate deposits can be processed by calcination and by selective acid leaching methods. However, calcination has some drawbacks and selective leaching with organic acids is a promising method for the beneficiation of this type of ore. In this paper, the leaching of calcareous phosphate ores proposed in the literature is reviewed with the aim of identifying the important factors involved in the dissolution process. The literature indicates that the organic acid reagent, acid concentration, reaction time, solid/liquid ratio, temperature, particle size distribution and stirring speed are important parameters in the process. The range and optimum values of these parameters reported in the literature are summarized, but there is still some doubt regarding the optimum reaction time. Analysis of the leaching kinetic data and activation energy show that the leaching reaction is chemically controlled. Limited consideration is given to the economic aspects of organic acid leaching. The leaching method appears to be cheap, but a complete economic evaluation is required for each ore, dependent upon the local price of the organic acids used and the cost of their recovery. It is proposed that future research should focus on the leaching characteristics of specific calcareous phosphate ores and on the development of a methodology to optimise leaching using organic acids.
Abu-Eishah, S.I., E1-JaUad, I.S., Muthaker, M., Touqan, N. and Sadeddin, W., 1991. Beneficiation of calcareous phosphate rocks using dilute acetic acid solutions: optimisation of operating conditions for Ruseifa (Jordan) phosphate. Int. J. Miner. Process., 31: 115-126.
Polish Journal of Chemical Technology, 2016
In this work, some parameters during the partial acidulation by phosphoric acid of phosphate 53.75% BPL (bone phosphate of lime) having different particle sizes are determined. P2O5 recovery is obtained by performing a series of reactions using phosphoric acid diluted from 10 to 40 wt.% and with reaction times ranging from 10 to 50 minutes. The best conversion rates are obtained with the following reaction parameters: phosphates size: 88-177 μm, reaction time: 50 minutes and phosphoric acid concentration: 40 wt.%. In the second part, the water-soluble P2O5 of PAPRs (Partially Acidulated Phosphate Rocks) obtained with phosphoric acid 30% and 40 wt.% is measured. The results of experiments showed that the water-soluble P2O5 has reached 15.2% for PAPRs obtained by reacting phosphate 88 μm with phosphoric acid 40 wt%.
Dissolution of Calcareous Phosphate Rock from Gafsa (Tunisia) Using Dilute Phosphoric Acid Solution
International Journal of Nonferrous Metallurgy, 2014
In the present study, porous structure of raw and calcined phosphate ore particles was examined. The specific surface area and the pore volume were determined by nitrogen adsorption. Raw particles and calcined ores were leached using dilute phosphoric acid solution (4% P 2 O 5). In all cases, the ESEM (Environmental Scanning Electron Microscopy) observations show that the grain of phosphate holds its shape ovoidale. The sample heated at 780˚C presented the lowest specific surface area 0.6 m 2 /g at each reaction time, and the unreacted phases were analysed using XRD, FT-IR, Nitrogen adsorption and ESEM observations. The selective leaching curves were evaluated in order to test the validity of kinetics models. A mathematical model in the following form was applied: (() − − = ln 1 α m kt). The dissolution of the two samples (raw and calcined phosphate) has been observed to take place in two steps: the first being fast and the second being slow.
1994
Original phosphate rocks (PR) and water insoluble residues (WIR) from mixtures of reactive PRs and single superphosphate, known commercially as longlife single superphosphate (LLSSP), and from partially acidulated PRs (PAPR), were compared in terms of their elemental content, chemical reactivity as indicated by the apatite unit cell 'a' dimension and solubility. Phosphate rock reactivity is known to be inversely related to the 'a' dimension. Partial acidulation (20%) with commercial grade phosphoric acid resulted in an increase in aluminium (A1), iron (Fe) and fluoride (F) concentrations in the WIRs. The apatite 'a' dimensions of WIRs from LLSSPs were greater than those of the respective original North Carolina (NC), Khouribga (KR), Jordan (JR), Sechura (SE) and Arad (AR) PRs added to single superphosphate (SSP), made from Nauru PR (NR)) to produce the LLSSPs. This was attributed to the presence of the less reactive NR in the WIRs left-over from the SSR Partial acidulation with phosphoric acid increased the apatite 'a' dimensions of NC and E1Hassa (EH) PRs. The increase in apatite 'a' dimension of NC and EH was probably due to selective dissolution of a more reactive fraction of the PRs during partial acidulation. Changes in the apatite 'a' dimension following partial acidulation with phosphoric acid were not significant for the other PRs studied, e.g. Gafsa (GF), KR and AR, although differential X-ray diffractograms (DXRD) indicated that the material dissolved during partial acidulation was more reactive than the WIRs and the original PRs. The apatite 'a' dimension of NC PR was not affected by pretreatment with 2% or 4% citric acid (CTA). The contrasting response in 'a' of NC PR to acidulation with phosphoric and citric acids may be related to differences in the strength of these acids, and/or to the differing environments under which the reactions took place.
Special Topics & Reviews in Porous Media - An International Journal, 2010
The reactivity of calcined Tunisian phosphate ore was studied in both phosphoric and acetic solutions. Phase analysis from X-ray diffraction and IR absorption data indicate that carbonate apatite, or francolite, and fluorapatite are the main phases. However, it was observed that the calcium oxide phase, evident at the most intense peak (d=2.401Å;2θ= 37.42 •) and at the adsorbant band at around 700 cm −1 disappeared or were weakly defined for the solid leached in acetic medium. Nitrogen adsorption-desorption analysis shows a rising of mesopores at the surface of the leached particles and then an increase of their specific surface area, SBET. The scanning electron microscope micrographs of the particles and their size distribution show a constancy of their outer dimensions during attack.
Phosphate Rock Treatment with Hydrochloric Acid for Increasing P2O5 Content
The present paper deals with the treatment of phosphate obtained from a commercial sample of Akashat phosphate ore in hydrochloric acid. The factors studied are effects of the temperature of dissolution, acid concentration, and the time required for mixing phases. The experiments were performed with 100 kg/m3 of solid/liquid ratio, the size of the particles ranged 125-140 μm, the initial acid concentrations were 20, 30 and 40 wt% HCl, and the temperature of dissolution was kept constant at 30, 40, 50, 60 and 70 oC. The results indicated that the percentage of P2O5 increases as the HCl concentration increased using different time and temperatures. Also, the results showed that the best conditions for P2O5 recovery process according were acid concentration 40%, reaction time of 90 min, and temperature 30 oC.
Minerals
The increasing need for phosphorus and rare earth elements (REEs) has initiated the studies of new mineral deposits and new complex processing technologies. Estonian phosphate rock (EPR) resources, which are not in use, are estimated to be more than 3 billion metric tons or 800 million tons of P2O5. The experiments of dissolution of three different EPR samples in hydrochloric acid were carried out with the aim of studying the impact of the chemical and mineralogical composition of EPR on the leaching process. The leaching of P, Ca, Mg, and consumption of H+ ions depend on HCl concentration and dosage. The solubility of fluorine and REEs are also influenced by CaF2 and REEs-phosphates precipitation. Fe solubility depends on the mineralogical composition of EPR but also on particle size, acid dosage, pH, and phosphorus content in the solution. The dissolution of pyrite is much lower than the solubility of carbonate apatite. Dolomite dissolution depends on the acid dosage and the fract...
Solubility test in some phosphate rocks and their potential for direct application in soil
2009
There are various methods to evaluating phosphate rock for direct application. The first approach is solubility test of Phosphate Rocks (PR) using chemical extractant. In this study to compare the effectiveness of direct application of PRs, two samples of a sedimentary unbeneficiated PR from Lar mine of Yasooj and two samples of concentrated PR of Asfordi igneous PR of Yazd in Iran along with one sample PR of Gafsa (Tunisia) were analyzed for the main nutrients and minerals with XRF and XRD. Calcite and quartz were the main ingredients of Yasooj PR which cause problems for direct application. Yazd PR in addition to apatite had some iron and magnesium minerals which are also undesirable for fertilizer producing. The reactivity of these PRs was determined using the common extractants (Formic Acid, Citric Acid and Neutral Ammonium Citrate) and classified on the basis of International Fertilizer Development Center (IFDC) proposed classification method for direct application. The reactivity of Iranian PRs was quite low compare to Gafsa PR. The long-term dissolution kinetics of these PRs were determined with Formic Acid (FA) and Citric Acid (CA) showed slow reaction initially (0-20 min.) because of the presence of free calcium carbonate but later on the reaction rate increased surpassing Gafsa PR. Therefore Yasooj PR could be recommended to use in soil after beneficiation and removal of lime. The kinetics of dissolution of Yazd PRs followed a zero order equation.