Printed Edition of the Special Issue Published in Minerals

In the context of sustainable mining and circular economy objectives, this special issue highlights some environmentally friendly and green solutions for the recycling and management of waste rock from phosphate mining, tailings and phosphogypsum. Within the framework of sustainable mining and circular economy objectives, several environmentally friendly and green solutions for the recycling and management of phosphate mine tailings, tailings and phosphogypsum rock are highlighted in this special issue.

Review on Beneficiation Techniques and Reagents Used for Phosphate Ores

• Introduction
• Beneficiation Techniques for Phosphate Ores 1. Flotation
• Factors Affecting the Flotation of Phosphate Ore
• Summary

Various depressants used for flotation of phosphate ores are collected and presented in Table 2. The depression effect and mechanism of NSFC on dolomite in the flotation of phosphate ores. Sept.

Figure 1. The reverse “Crago” double float process for beneficiation of Florida phosphate ore [6].

The Beneficiation Processes of Low-Grade

Sedimentary Phosphates of Tozeur-Nefta Deposit (Gafsa-Metlaoui Basin: South of Tunisia)

Materials and Methods 1. Sampling and Separation

The trench sampling method was used to extract 400 kg of crude phosphate material from the roof series of the Tozeur-Nefta deposit. The particle size distribution was measured using the wet set method (AFNOR) (size range from 0.40 to 10 mm).

Table 1. Characteristics of grinding balls.

Results and Discussion 1. Petrographic Analysis

The increase in grain surface area can increase the reactivity with the flotation reagents [50]. During the flotation tests, two parameters were varied: the pH of the pulp and reagents.

Figure 2. X-ray diffractogram of the raw phosphate sample showing the presence of: carbonate- carbonate-fluorapatite (Cfa), calcite (Cal), dolomite (Dol), illite (Ill), kaolinite (Kln), gypsum (Gp) and quartz (Qtz).

Conclusions

Double reverse flotation of a very low grade sedimentary phosphate rock, rich in carbonate and silicate.Int. Beneficiation of Mardin-Mazıda ˘gi (Turkey) calcareous phosphate rock using dilute acetic acid solutions.Chem.

A Comparative Study of Different Columns Sizes for Ultrafine Apatite Flotation

• Experimental 1. Ore Sample
• Flotation Studies 1. Reagents
• Results and Discussion 1. Desliming
• Conclusions

The performance (grade and recovery) of coarser drift in the 6” diameter column was better than the results obtained for the 4” diameter column. Regarding cleaner flotation, it could be observed that the results obtained in the flotation with the 2”.

Table 1. Chemical analysis of the slime samples.

Rare Earth Occurrences in Streams of Processing a Phosphate Ore

Materials and Methods

Because the enrichment is a physical process, the REE-bearing phases in the concentrate and tailings are the same as in the ore. The modal mineralogy (i.e., the percentages of the mineral components), the mineral liberation and the grain size distribution of REE-bearing minerals were measured using a mineral liberation analyzer (MLA) (an FEI MLA Quanta 600 system) at the Geological Survey of Finland in Outokumpu. Using the EDS analysis, the composition of a certain mineral was determined and the composition was compared with the composition of the mineral as specified in the MinIdent mineralogy database and a mineralogical book [26].

Using a combination of MLA and EPMA analyses, the REE concentrations contributed by all REE-bearing phases in the samples are determined. Then, the occurrence of REEs, for example the weight distribution of REEs in phosphate rock processing streams with REE-bearing phases, is obtained by combining experimental and commercial production data.

Table 2. The limits of detection (LODs) of the EPMA for REEs with sample phosphogypsum (PG) (mg/kg).

Results

The recoveries of REEs measured by the TREO content in the concentrate and the residues of the ore for different REE-bearing phases were calculated based on the REO concentration data shown in Figures 2-4 and in Table 8. The total recovery of the TREO content in the concentrate and the residues is 74.1% and 22.0%, respectively. Recovery of total rare earth oxide (TREO) in the concentrate and residues of various REE-containing minerals.

The other REE-bearing phase listed in the table is not a distinct mineral identified by MLA and EPMA. Because the recovery of TREO in the concentrate is 74.1%, the recovery of TREO in the PG from the ore is 63.0%.

Table 6. Modal mineralogy of the ore and flotation concentrate by mineral liberation analyser (MLA).

Discussion

Development of the Polish waste-free technology of using apatite phosphogypsum with the extraction of rare earths.J. Investigation of the acid leaching process of rare earth elements from phosphogypsum using HCl, HNO3 and H2SO4. Hydrometallurgy. Valorization of deposited stocks of industrial process residues containing rare earths: phosphogypsum and red mud.

Mineral Processing and Extraction of Rare Earth Elements from the Wadi Khamal Nelsonite Ore, Northwestern Saudi Arabia.Arabic. REE behavior during anhydrite and gypsum formations of Kuroko-type massive sulfide-sulphate deposits.

Geochemical Characteristics of Dolomitic

Phosphorite Containing Rare Earth Elements and Its Weathered Ore

Materials and Methods 1. Materials

• SEM-EDX

In order to identify the mineral composition of phosphorite samples, an X-ray powder diffractometer (Rigaku D/MAX 2500, Tokyo, Japan) was applied using Cu Kαradiation (40 kV, 100 mA). The morphology was studied using backscattered electrons (BSE) and the composition of the different phases using EDX [24-26]. To determine the presence of REE, phosphorite samples were leached with different acids and inorganic salts [17].

It is necessary to perform mathematical analysis for the content of phosphorus and rare earth elements in phosphate rock and to calculate their average value and average variance. If the ratio of the mean value and the mean variance of the two are significantly different (generally considered to be 20%), the rare earth will exist as an independent mineral; otherwise, it will exist in a dispersed form such as homogeneity, adsorption, etc.

Table 1. Cont.

Results and Discussion

Therefore, it is believed that the rare earth elements are unlikely to exist as an independent mineral [15,31,32]. Rare earth elements can exist in the form of independent minerals or isomorphic substitution in the minerals' lattices. The rare-earth features indicated that the phosphorite deposits are normal marine sedimentary rocks.

Process investigation of the acid leaching of rare earth elements from phosphogypsum using HCl, HNO3 and H2SO4. Hydrometallurgy. Mode of occurrence of rare earth elements in phosphorite in Zhijin District, Guizhou Province, China.Acta Mineral.

Figure 1. X-ray diffraction (XRD) patterns of studied phosphorite samples.

Rare Earth Element Recovery from Acidic Extracts of Florida Phosphate Mining Materials Using Chelating

Results and Discussion 1. Acid Extraction

The results of this study indicate that this polymer efficiently recovers rare earth elements from acid extracts of phosphate mine waste products. The recovery of rare earth elements from phosphate rock and phosphate mine waste products using a novel water-insoluble adsorption polymer. Rare earth elements in sedimentary phosphate deposits: Solution to the global REE crisis?Gondwana Res.

Leaching and recovery of phosphate and rare earth elements from an iron-rich fluorapatite concentrate: Part II: Selective leaching of calcium and phosphate and acid roasting of the residue. Hydrometallurgy. Leaching of rare earth elements (REE) and impurities from phosphogypsum: A preliminary overview for further recovery of critical raw materials.

Figure 2. Extracted REEs using mixtures of (a) HNO 3 , (b) H 2 SO 4 , citric acid, and ascorbic acid.

Phosphate Mine Tailing Recycling in Membrane Filter Manufacturing: Microstructure and

Filtration Suitability

Materials and Experimental Techniques 1. Materials

Changes in the technological properties (Yi) of the membranes compared to processing factors (sawdust addition (τ), temperature (T) and soaking time (t)) were estimated using a second-order polynomial model [16,36,37]. The permeability coefficient values ​​showed a marked difference between the behavior of clay and phosphate mud. The latter has the effect of reducing the permeate flow due to an increase in the hydraulic resistance of the system (as explained earlier).

The experimental conditions of the planned experiments and the measured properties are given in Table 5. The weights of the effects of the studied factors on the studied properties follow the order: t>τ>.

Figure 1. X-ray diffraction patterns of phosphate sludge (PS) and a dolomite-rich clay (SA)

Valorization of Phosphate Mine Waste Rocks as Materials for Road Construction

Materials and Methods 1. Materials Sampling

The chemical composition of the solid samples was analyzed by X-ray fluorescence (Panalytical, Epsilon 4 Model, Malvern Panalytical, Malvern, UK) and liquid solutions were analyzed by inductively coupled plasma atomic emission spectroscopy (ICP-AES) (Perkin Elmer Optima 3100 Walham, USARL, MAElmer, USARL). The 0/400μm fraction of the investigated samples has been subjected to the plasticity test using the Atterberg limit method [30,31]. The shear strength parameters were investigated under the drained conditions of the 0/20 mm fraction of the investigated gray rock samples on the gray rock samples [40].

The dry densities of the materials were measured in situ using a membrane densitometer [42], while the measurement of the bearing capacity of the materials was evaluated through the determination of the modulus under static load at the plate EV2 (standard NF P 94-177-1). The speed was fixed at 4 km/h and the compaction energy of the machine was checked.

Figure 3. Summary of the followed methodology.

Results and Discussion 1. PMWR Characterization

In other words, the determination of the compaction energy that allows to have the maximum dry density. This is illustrated in the synoptic classification table according to the nature of the materials proposed by the NF P11-300 standard (Figure 6). The mineralogical composition of the studied materials also showed plagioclase (albite and anorthite) and clays (illite which was only observed in samples I3, I4 and I5, therefore they showed most of the plasticity features).

Laboratory Evaluation of the Use of Alkaline Phosphate Wastes for the Control of Acid Mine Drainage.Mine Water Environ. Determination of the methylene blue of the soil by means of the spot test - Sols: Reconnaissance et essais; Association Française de Normalisation: Paris, France, 1998.

Table 1. Physical and geotechnical properties of collected materials.

Utilisation of Water-Washing Pre-Treated Phosphogypsum for Cemented Paste Backfill

Next, Figure 13 shows SEM images of the samples (mix ratio 3-OPG and 3-TPG) at different curing ages: on the left (Figure 13a, d) shows the morphology of samples after 7 days, in the middle (Figure 13b, e) are specimens after 14 days, and on the right (Figure 13c, f) they are after 28 days. The pretreatment with water washing effectively improved the transport mobility and efficiency of the TCPB mixtures. Experimental characterization of the influence of aggregate fineness and density on the quality of cemented paste backfill. Miner.

Numerical study of the pipeline flow properties of the cemented paste replenishment slurry taking hydration effects into account. The theoretical analysis of the influence of the particle size distribution of cement system on the properties of cement.Cem.

Figure 1. Flow chart of the experiments.

Durability Evaluation of Phosphogypsum-Based Cemented Backfill Through Drying-Wetting Cycles

Materials and methods

A drying-wetting test was adopted to accelerate the deterioration of the PG-based back specimens. Thus, the porosity of the backfill samples was measured to evaluate the mechanical performance of the PG-based backfill. Figure 7 compares the UCS results of PG-based infill specimens exposed to different rinse solutions after and 30 drying–wetting cycles.

Unlimited compressive strength of the PG based backfill samples at different dry-wet cycles and exposure solutions. When exposed to the saline solutions, the UCS of the samples decreased significantly by approximately 40%.

Figure 1. Particle size distributions of the phosphogypsum and binder.

Radioactivity of Five Typical General Industrial Solid Wastes and its Influence in Solid Waste Recycling

Materials and Methods 1. Samples

Alkali-activated EMR can replace part of the cement used to prepare building materials. The external radiation index (Iγ) refers to the sum of the specific activity ratio of 226Ra, 232Th and 40K in building materials at their respective standard limits. The specific activity limit of 226Ra in building materials specified in GB6566-2010 is 200 Bq/kg, considering only indoor radiation conditions.

The radium equivalent activity (Raeq) [45] was used to compare the relative gamma radioactivity of 226Ra, 232Th and 40K in building materials. When the ratio of CRa,CTh and CK are all intended to be zero, the ratio of f was calculated using Equations (11) and (12) the maximum dose of solid waste in building materials.

Results and Discussion 1. Activity Concentration

These findings provide a basis for the above-mentioned solid waste reduction in Guizhou in the field of building materials. Radionuclide content and associated radiation hazards of building materials and by-products in Baoji, Western China.Radiat. Determination of natural radioactivity and associated radiation hazard in building materials used in Weinan, China.Radiat.

Natural radioactivity and human exposure from raw materials and final product from the cement industry used as building materials. Radiation. KTA-OECD.Radiation exposure from natural radioactivity in building materials: Report from an OECD Nuclear Energy Agency export group; KTA-OECD: Paris, France, 1979; page

Figure 1. Variation of 238 U activity concentration versus (a) 235 U activity and (b) 226 Ra activity.