Jordanian phosphate deposits are part of the Upper Cretaceous (Campanian-Maastrichtian) sedimentary sequence, which covers approximately 60% of the country [4][8][13]-[18].

At Eshidiya Mine, the phosphate occurs in laterally continuous beds subdivided into three principal economic horizons: A1 (Upper), A2 (Middle), and A3 (Lower) [19]. These horizons differ in thickness, grade, and impurity content of P₂O₅ (Figure 2).

Figure 2. Lithological section of Eshidiya mine.

The A2 layer is generally the highest-grade unit, with TCP values reaching 71% - 74%, and is often marketed after minimal processing. In contrast, the A1 and A3 layers typically require beneficiation to meet commercial specifications. Mineralogically, the phosphate rock is dominated by apatite, primarily carbonate fluorapatite (francolite), accompanied by varying proportions of calcite, quartz, and clay minerals [4][5].

Eshidiya Mine is operated by using open-pit mining methods. Run-of-mine ore is crushed and screened at 12.5 mm. Oversize material is currently classified as reject, while undersize fractions undergo washing, and for the A3 layer, additional flotation carried out to reduce the silica content. Washing processes generate significant volumes of fine slime, which are pumped to evaporation ponds. These reject and slime streams form the focus of the present investigation as described in Figure 3.

Beneficiation tests were designed to reflect practical, low-cost processing options (Figure 3). Coarse rejects were jaw-crushed with a gap setting of 10 mm to achieve a target P80 of <4 mm. The crushed material was then subjected to wet sieving, where:

A1Reject: Simple washing was performed at a water-to-solids ratio of 3:1 (v/w) with 10 minutes of agitation, followed by wet sieving at 2.0, 1.0, and 0.75 mm. No desliming was applied prior to sieving.A2Reject: Simple wet sieving was conducted at the same size fractions without a prior washing stage (5 minutes screening time per fraction).A3Reject: Multistage washing involved four successive stages, each at a 3:1 water-to-solids ratio with 10 minutes of agitation and scrubbing. After the final stage, the material was wet-screened at 2.0, 1.0, and 0.75 mm.

Preliminary particle-size distribution (PSD) analysis of the rejects indicated that phosphate (francolite) was sufficiently liberated below 4 mm. Qualitative SEM/XRD observation of the −0.75 mm fraction confirmed that fines were enriched in liberated apatite micro-crystals, justifying the selected grind size and the effectiveness of washing for clay removal.

Figure 3. Mineral processing diagram of phospahte at Eshediya mine.

Mineralogical characterization was performed using X-ray diffraction (XRD), optical microscopy, and scanning electron microscopy (SEM). The Major oxide composition was determined by X-ray fluorescence (XRF), including P₂O₅, CaO, SiO₂, Al₂O₃, Fe₂O₃, and minor constituents.

All phosphate grades in this study were analytically determined as P₂O₅. Tricalcium phosphate (TCP) values reported throughout the manuscript were calculated using the standard industrial conversion factor TCP (%) = P₂O₅ (%) × 2.186, in accordance with JPMC operational and regional marketing practice. Acidinsoluble residue (AIR) was determined by hydrochloric acid digestion, and chloride content was measured potentiometrically.

The Jordanian phosphates are composed mainly of pellets, intraclasts, skeletal fragments, and coated grains, consistent with previous studies on Upper Cretaceous phosphorites in Jordan [5][18][19]. Petrographic examination reveals that the phosphate is predominantly of grainstone to pelletal type, interpreted as a reworked product of synsedimentary phosphatized mud deposited in low-energy, organic-rich marine environments [20]-[24]. The processing of washing and transport would concentrate the phosphorite particles “Pellets” generated as phosphorite beds within tectonic troughs in near shore setting due to upwelling [24]. Phosphate rocks are mostly composed of different varieties of apatite. Generally, they include fluorapatite, carbonate-flourapatite (francolite), carbonate hydroxylapatite (dahlite) and chlor-apatite.

The composition of phosphate in the study area is similar to other phosphates in Jordan, with small differences in the amount of the phosphatic particles and silica content. As a rule grains constitute most of the phosphatic part of phosphate layers. The matrix is usually siliceous and locally calcite (sparitic or micritic type). Clay minerals and phosphatic matrices are also present in the groundmass of the rock.

Microscopic observations (Figure 4(A), Figure 4(B)) show isotropic yellow–brown phosphate filling skeletal materials (bones and fish teeth) and occurring as microcrystalline aggregates surrounded by quartz and micritic calcite. SEM backscattered electron images confirm the dense microcrystalline nature of the apatite infilling skeletal fragments (Figure 4(C), Figure 4(D)).

Figure 4. (A) Isotropic phosphate (yellow brown color) filling skeletal materials, surrounded by quartz grains (colorless) and micritic calcite (PPL, ×50); (B) Isotropic phosphate filling fish teeth (yellow brown color), surrounded by quartz grains (colorless) and micritic calcite (PPL, ×50); (C) SEM backscattered electron image of microcrystalline phosphate filling bone fragments (×18); (D) SEM backscattered electron image of microcrystalline phosphate filling microskeletal materials (×390).

X-ray diffraction analysis confirms that the dominant phosphate mineral is carbonate fluorapatite type (francolite), with gangue minerals of quartz and calcite as secondary minerals (Figure 5).

Table 1 summarizes the chemical composition of the unprocessed head samples from the three phosphate layers. The A2 layer exhibits the highest grade, with

Figure 5. XRD pattern showing apatite (francolite), quartz and calcite as the main mineral composition of study phosphate.

TCP values of approximately 73%, while the A1 and A3 layers show lower TCP contents 55% and 48%, respectively, and higher acid-insoluble residue (AIR) 22.75%, and 22.50%, respectively, reflecting higher siliceous impurity levels. The Cl content varies between 750 and 800 ppm in three layers that indicating similar sedimentary environment condition of phosphate formation (Table 1).

Table 1. Chemical analysis of head samples before processing.

After crushing and sieving, reject materials from A1 and A2 exhibited TCP values closely matching those of processed ore, where A1 from plant product reach up to 68.0% (after washing); A2 from plant product reach up to 74.0% (after sieving), whereas A3 as washed reject reach up to 57.9% (Table 2). For A1, the average TCP of rejects was 67.2% (Table 3), and A2 rejects averaged 70.7% TCP (Table 4), whereas A3 rejects responded positively to multi-stage washing, with TCP increasing from 48% in the head sample to an average of 57.9% in the washed reject material (Table 2 and Table 5). Meanwhile, mineral processing effectively reduced chloride and acid-insoluble residue (AIR) content in the A1 and A3 layers, as detailed in Table 2 and shown in Figure 6.

Wet sieving of crushed reject material demonstrates that fine fractions are consistently enriched in phosphate. For the A1 reject, TCP values range between 66.2% and 68.1%, with an average of 67.2% as shown in Table 3.

Table 2. Chemical analysis of Key Streams after processing.

(a) (b)

Figure 6. Comparison of TCP, AIR, and Cl values for the three phosphate layers before processing (head sample) and after processing. Note: “After Processing” for A3 represents the washed reject stream (this study), not the plant product.

Table 3. Wet sieving results for A1 reject sample.

Similar trends were observed for the A2 reject material, where TCP values have average of 70.7% after wet sieving as shown in Table 4.

Table 4. Wet sieving results for A2 rejects sample.

For the A3 layer, multistage washing increased TCP values from 48% in the head sample to an average of 57.9% in the reject material as shown in Table 5.

Table 5. Wet sieving results for A3 reject sample after washing.

Operationally, the slime corresponds predominantly to the −0.75 mm size fraction generated during the washing circuit. This fine fraction consists mainly of clay-sized particles and liberated apatite micro-crystals, as supported by SEM and XRD observations. The chemical composition of the slime produced from the A1 washing circuit is summarized in Table 6 and Table7 and illustrated in Figure 7. The slime fraction contains substantial phosphate values, with total phosphate (TCP) ranging from 45.0 to 47.3 wt.% and an average of 46.15 wt.%, indicating that a significant proportion of phosphate is lost to the fine-sized fraction during washing. In addition, the chlorine (Cl) content decreases to 471 ppm in the slime compared with 750 ppm in the head sample. In contrast, the acid-insoluble residue (AIR) increases to 26.7 wt.% relative to 22.75 wt.% in the head sample, reflecting an enrichment of gangue minerals in the fine fraction (Figure 7).

Table 6. Major oxide composition (XRF) of A1 slime sample.

Table 7. Summary chemical parameters of A1 slime compared with head sample.

A simplified mass balance was conducted for the beneficiation tests on reject material. Table 8 presents the mass yield (%) for the product (+0.75 mm fraction), (72.8% for A3 (reject washed; 88.5% for A2 reject and 85.2% for A1 reject), whereas the TCP recovery was 81.1% for A3 (washed reject); 89.4 (%) for A2 reject and 86.1% for A1 reject, relative to the crushed reject feed for each layer. This confirming the resource potential of these waste streams. It should be noticed that the feed of TCP % is the weighted average of the crushed reject before sieving. Product refers to the combined +0.75 mm fractions, whereas slime (−0.75 mm) and moisture losses account for the remaining mass.

(a) (b)

Figure 7. Comparison between TCP, AIR and Cl values of A1 head sample and slime.

Table 8. Mass balance and TCP recovery from reject processing.

The analytical results demonstrate that coarse reject materials from A1 and A2 are of remarkably high grade, with TCP levels only marginally below those of the saleable product. This suggests that the current practice of rejecting +12.5 mm material is based on historical processing constraints rather than quality considerations. Re-crushing and refeeding this material into the beneficiation circuit could recover significant phosphate units without substantial additional processing cost.

For A3, the reject material is lower in grade and higher in silica, but multi-stage washing achieved a TCP increase from 48% in the head sample to 57.9% in the washed reject (Table 5), with a corresponding TCP recovery of 81.1% (Table 8). This demonstrates a significant upgrade potential through simple hydraulic methods. Although flotation represents an effective long-term solution for fine slime upgrading, the present study prioritizes low-cost and immediately deployable processing routes that can be integrated into existing JPMC infrastructure with minimal capital investment. Flotation-based upgrading of slime is therefore recommended as a subsequent optimization stage.

The slime sample, though high in acidinsoluble residue, contains ~46% TCP. This material could be used in several ways: 1) as a filler in phosphate-based products, 2) blended with higher-grade concentrates for specific fertilizer formulations, or 3) pelletized for direct application in agriculture. Successful slime utilization would also mitigate the environmental risks associated with large-scale tailings storage [24][25].

Integrating reject and slime streams into the production cycle aligns with circular economy principles, which aim to minimize waste and maximize resource efficiency [25]. For Eshidiya, this approach could lead to extend mine life by converting waste into reserve; reduce land disturbance and tailings footprint; lower specific water and energy consumption per ton of phosphate produced and enhance economic resilience by creating value from previously discarded stockpiled. These findings contribute to our understanding of the mechanisms of nanoparticles-based collectors which facilitate the development of more efficient and environmentally friendly phosphorite collectors [8][25].

Quantitatively, if just 20% of the historically stockpiled reject (estimated at hundreds of thousands of tons) were recovered, it could add several years of production at current rates. This represents a tangible contribution to the sustainable development goals (SDGs), particularly SDG 12 (Responsible Consumption and Production) and SDG 9 (Industry, Innovation and Infrastructure) [26][27].

The most common key challenges could include: Processing costs that need additional crushing and handling may increase operational expenses; market acceptance related to blended, or lower-grade products must meet customer specifications; water management by re-processing of slime requires careful water-balance planning and regulatory framework, which is related to Jordanian mining policies that will may need updating to incentivize waste valorization [28].

It can be assumed that for industry and policy in phosphate mining should take into consideration immediate actions. JPMC should conduct a detailed audit of all reject stockpiles and slime ponds to quantify the recoverable resource. The pilot-scale trials should test the recrushing and re-processing of reject material in the existing plant [28]. Also medium-term strategies through investment in optimized crushing circuits to handle coarse rejects efficiently, develop blending formulations that incorporate slime into saleable products and to enhance water-recycling systems to make slime reprocessing sustainable [27]. The Jordanian Ministry of Energy and Mineral Resources should incorporate waste valorization into mining license agreements. Further research should assess the environmental life-cycle benefits of reject re-use and explore advanced beneficiation technologies for slime. This is aligned with the work of [29]-[31], that was carried out a factorial experimental design by flotation, which showed that the interaction between flotation parameters was significant on flotation recovery and concentrate grade. The order of significance was air flow rate, feed size, and sodium silicate dosage. Agitating and scrubbing of flotation feed was very significant on flotation recovery and concentrate grade especially with no grinding because of low phosphate particles liberation. The effect of slimes (fines) generated by such process on flotation performance can be reduced by using column flotation [30].

It can be argued that the high TCP content of coarse reject materials from the A1 and A2 layers demonstrates that their disposal is primarily a consequence of historical processing limitations rather than intrinsic ore quality. Re-crushing and reintroduction of this material into the beneficiation circuit could recover significant phosphate units with relatively modest additional costs. Although slime exhibits higher impurity levels, its moderate phosphate content opens several utilization pathways, including blending with higher-grade concentrates, pelletization for direct agricultural use, or application in specialized low-grade fertilizer products. Slime utilization would also substantially reduce the environmental footprint associated with tailings storage [31].

Integrating reject and slime streams into the production chain aligns strongly with circular economy principles. Such an approach can extend mine life, reduce waste volumes, lower land and water impacts, and enhance the long-term resilience of Jordan’s phosphate sector. From a policy perspective, incentivizing waste valorization through regulatory frameworks and mining licenses could accelerate the adoption of sustainable practices [32][33].