Clay Tailings Research Articles

Rheological Behavior of Clay Tailings in the Presence of Divalent Cations and Sodium Polyacrylate: Insights from Molecular Dynamics Simulations

This study analyzes the behavior of sodium polyacrylate (NaPA) as a rheological modifier for clay-based tailings. Special emphasis is placed on the impact of calcium and magnesium ions in industrial water, which are analyzed through rheograms, zeta potential measurements, and molecular dynamics simulations. The results are interpreted as electrostatic interactions, steric phenomena, and cation solvation. This interpretation integrates experimental studies with microscopic analyses, employing molecular dynamics simulations to elucidate the underlying mechanisms. In all cases, a decrease in the yield stress of synthetic slurries is observed as the dosing of NaPA increases due to greater repulsion between tailings particles through an increase in electrostatic repulsion and larger steric forces that hinder agglomeration. However, efficiency is reduced in the presence of divalent cations as zeta potential measurements suggest a reduction in the electrical charges of the particles and the polymer, making its application more challenging. The differences obtained in the presence of calcium compared to magnesium are explained in terms of the solvation of these ions and their impact on the polymer conformation in solution and adsorption on the mineral surfaces. This explanation is reinforced by molecular dynamics studies, which indicate that polymer adsorption on minerals depends on the type of mineral and type of ion. Particularly for quartz, the highest adsorption of NaPA occurs in the presence of calcium, whereas for a kaolinite surface, the highest polymer adsorption is obtained in the presence of magnesium. The competitive effect of these phenomena leads to the rheological behavior of the tailings being dominated by the effects originating in the clay.

Clay Tailings Flocculated in Seawater and Industrial Water: Analysis of Aggregates, Sedimentation, and Supernatant Quality.

High-molecular-weight anionic polyacrylamide was used to analyze the effect of kaolin on the structure of particle aggregates formed in freshwater and seawater. Batch flocculation experiments were performed to determine the size of the flocculated aggregates over time by using focused beam reflectance measurements. Sedimentation tests were performed to analyze the settling rate of the solid-liquid interface and the turbidity of the supernatant. Subsequently, a model that relates the hindered settling rate to the aggregate size was used to determine the mass fractal dimension (Df). Flocculation kinetics revealed that greater amounts of kaolin generated larger aggregates because of its lamellar morphology. The maximum size was between 10 and 20 s of flocculation under all conditions. However, the presence of kaolin reduced the settling rate. The fractal dimension decreased with the increase in the kaolin content, resulting in the formation of irregular and porous aggregates. By contrast, factors such as the flocculation time, water quality, and quartz size had limited influences on the fractal dimension. Seawater produced a clearer supernatant because of its higher ionic strength and precoagulation of particles. Notably, the harmful effect of clays in seawater was reduced.

Ceramic Tile Based on Local Hydromica Clay and Pegmatite Tailings

Ceramic Tile Based on Local Hydromica Clay and Pegmatite Tailings

Development of a novel eco-efficient LC2 conceptual cement based ultra-high performance concrete (UHPC) incorporating limestone powder and calcined clay tailings: Design and performances

This study presents an eco-efficient cement-limestone- calcined clay tailings ultra-high performance concrete (LC2 UHPC). On the basis of the D-optimal mixture design method, the LC2 UHPC recipes and fresh behaviors are firstly proposed and optimized. Then, the macro and micro characteristics of produced LC2 UHPC are evaluated. The obtained experimental results show that when the added total amount of limestone powder and calcined clay tailings reach 56.8% of the cementitious materials, the corrosion resistance properties of LC2 UHPC are optimized and advanced compared to normal UHPC. Afterwards, the microstructure and hydration properties of LC2 UHPC are presented. The ITZ of LC2 UHPC is denser than normal UHPC. Hydration degree of cement LC2 UHPC is higher. Moreover, the addition of limestone powder and calcined clay tailings can decrease the environmental impact by 37.1% compared to normal UHPC. The disadvantage of LC2 UHPC mainly is that the compressive strength and workability of LC2 UHPC is lower than normal UHPC. Considering the fact that the LC2 system is a low-carbon and more sustainable cementitious material than normal cement, the produced LC2 UHPC can be treated as an eco-friendly construction product, which is suitable to be wildly utilized to some area with plenty of clay sources in China in the future.

Reutilization Prospects of Diamond Clay Tailings at the Lomonosov Mine, Northwestern Russia

Approaches to reutilization of diamond clay tailings in northern environments are considered in the example of the Subarctic region of Russia. The monitoring studies are conducted at storage facilities of Severalmaz PJSC where ca. 14 million cubic meters of waste rock are produced annually after kimberlite mining and processing. The tailings of diamond ore dressing waste are situated in complex geological conditions of high-groundwater influx and harsh cold climate with low levels of solar radiation and the average annual temperature below freezing point. Furthermore, the adjoining protected forests with a significant diversity of biogeocenoses and salmon-spawning rivers are affected by the storage area. Reducing the impact of the tailings can be achieved through the reuse of the stored clay magnesia rocks obtained from saponite-containing suspension. The experiments reveal the most promising ways of their application as potential secondary mineral raw materials: cement clinker and ceramics manufacture, integration of alkaline clay into the reclamation of acidic peat bogs, and production of aqueous clay-based drilling fluid. Field and laboratory tests expose the advantages and prospects of each suggested treatment technique.

Formation of closed-pore foam ceramic from granite scraps

Utilization of granite scraps and minor clay tailings to prepare closed-pore foam ceramic was investigated using SiC as foaming agent. The foam ceramic presented promising results with a bulk density of 237.4kg/m3, compressive strength of 0.85MPa, flexural strength of 0.42MPa, porosity of 83.31%, water absorption of 2.21% and thermal conductivity of 0.051W/(mk), which had good potential application in the field of building insulation.

The efficiency of inorganic immobilization agents to stabilize tailings from the mine

Toxic metals, which are found in waste sludge from mine tailings of lead and zinc Sase, were immobilized with different compaction imobilazacionim agents (indigenous clay, red mud ) in the monoliths of different proportions. The efficiency of immobilization procedures was monitored using diffusion leaching tests (ANS 16.1). Also, certain parameters (coefficients of diffusion, leachability index) were determined to be used for evaluating the efficiency of immobilization techniques previously applied. In the treatment of tailings with clay and red mud can be observed decrease in mobility of metals (Cr, Ni, As, Pb and Zn) with an increase in the percentage of added red mud, while the Cu and Cd comes to deviations. A mixture of clay tailings and red mud proved to be a very good immobilization agent for all treated metals.

CaO–MgO–Al2O3–SiO2 glass-ceramics from lithium porcelain clay tailings for new building materials

Lithium porcelain clay tailings (containing 1.2wt.% Li2O) blended with other chemical raw materials were used to develop a new glass-ceramic of CaO–MgO–Al2O3–SiO2 system for rolling process. The effects of TiO2 and ZnO oxides on melting and crystallization behaviors of glasses were investigated by DTA, XRD, EPMA and viscosity test. The results showed that melting temperature, forming temperature and glass transition temperature (Tg) of glasses were decreased with the increase of ZnO addition. Nevertheless, the crystallization temperature was shifted from 864 to 901°C when the addition of TiO2 decreased from 2wt.% to 0.5wt.%. Diopside as a major crystalline phase and spinel as a minor phase are precipitated in M3 specimen with 2.5wt.% ZnO and 0.5wt.% TiO2. The columnar and granular crystalline phases were distributed in M3 specimen nucleated at 750°C for 2h and followed by crystallization at 1110°C for 2h, which resulted in proper appearance suitable for decorative materials.

The Effect of Switchable Water Additives on Clay Settling

The recycling of process water from strip mining extractions is a very relevant task both industrially and environmentally. The sedimentation of fine tailings during such processes, however, can often require long periods of time and/or the addition of flocculants which make later water recycling difficult. We propose the use of switchable water additives as reversible flocculants for clay/water suspensions. Switchable water additives are compounds such as diamines that make it possible to reversibly control the ionic strength of an aqueous solution. Addition of CO(2) to such an aqueous solution causes the ionic strength to rise dramatically, and the change is reversed upon removal of the CO(2). These additives, while in the presence of CO(2), promote the aggregation of clay tailings, reduce settling times, and greatly increase the clarity of the liberated water. The removal of CO(2) from the liberated water regenerates a low ionic strength solution that does not promote clay aggregation and settling until CO(2) is added again. Such reversible behavior would be useful in applications such as oil sands separations in which the recycled water must not promote aggregation. When added to kaolinite and montmorillonite clay suspensions, switchable water provided process waters of lower turbidity than those additives from inorganic salts or by CO(2)-treatment alone. When recollected, the switchable water supernatant was shown to be recyclable over three cycles for enhanced settling of kaolinite.

Artificial soils from alluvial tin mining wastes in Malaysia – A study of soil chemistry following experimental treatments and the impact of mycorrhizal treatment on growth and foliar chemistry

For decades Malaysia was the world's largest producer of Sn, but now the vast open cast mining operations have left a legacy of some 100,000 ha of what is effectively wasteland, covered with a mosaic of tailings and lagoons. Few plants naturally recolonise these areas. The demand for such land for both urban expansion and agricultural use has presented an urgent need for better characterisation. This study reports on the formation of artificial soils from alluvial Sn mining waste with a focus on the effects of experimental treatments on soil chemistry. Soil organic matter, clay, and pH were manipulated in a controlled environment. Adding both clay tailings and peat enhanced the cation exchange capacity of sand tailings but also reduced the pH. The addition of peat reduced the extractable levels of some elements but increased the availability of Ca and Mg, thus proving beneficial. The use of clay tailings increased the levels of macro and micronutrients but also released Al, As, La, Pb and U. Additionally, the effects of soil mix and mycorrhizal treatments on growth and foliar chemistry were studied. Two plant species were selected: Panicum milicaeum and Pueraria phaseoloides. Different growth patterns were observed with respect to the additions of peat and clay. The results for mycorrhizal treatment (live inoculum or sterile carrier medium) are more complex, but both resulted in improved growth. The use of mycorrhizal fungi could greatly enhance rehabilitation efforts on sand tailings.

Oak Flat Restoration on Phosphate‐Mine Spoils

Abstract Phosphate mining in Beaufort County, North Carolina, impacts a rare plant community type, oak flats (nonriverine wet hardwood forests [NRWHF]). Reclamation of land after mining utilizes three by‐products of mining and manufacturing: clay tailings containing dolomite, low‐pH phosphogypsum, and bucket‐wheel spoil from the surface 10 m. The open mine is backfilled with a blend of phosphogypsum and clay tailings, which may be left as the surface or capped with bucket‐wheel spoil. The objective of this study was to determine the feasibility of using these by‐products as substrates for restoring NRWHF. A field study measured survival of 11 tree and four shrub species planted in replicated plots of blend or bucket‐wheel spoil. Survival at the end of the second growing season was 59% on the blend and 52% on the bucket‐wheel spoil. A greenhouse experiment compared growth of four species of NRWHF oaks on bucket‐wheel spoil, blend, local topsoil (sterilized and unsterilized), and a commercial potting mix. Germination rates of acorns of all four species planted in topsoil were almost double those in bucket‐wheel spoil and 1.5 times greater than those in the blend. Height and stem volume of trees were significantly greater when grown in topsoil than in bucket‐wheel spoil and blend. There was no difference in tree growth on bucket‐wheel spoil and blend. In field and greenhouse soil tests, the blend had cadmium levels over 100 times that of local topsoil and the bucket‐wheel spoil had levels 40 times greater. Leaf chemical analysis in the field and greenhouse found higher cadmium levels in plants grown on the blend than on the bucket‐wheel spoil. These results indicate that the use of topsoil from the advancing mine front may lead to successful restoration of NRWHF.

Optimising the dewatering behaviour of clay tailings through interfacial chemistry, orthokinetic flocculation and controlled shear

The effect of shear on dewatering behaviour and particle interactions of Na-exchanged smectite and kaolinite clay dispersions has been investigated at pH 7.5, using hydrolysable Ca(II) and Mn(II) ions as coagulants and high molecular weight anionic and non-ionic polyacrylamide (PAM A and PAM N, respectively) and polyethylene oxide (PEO) flocculants. Metal ion addition enhanced the flocculation performance by dramatically reducing the magnitude of the particle zeta potential and, in the case of smectite pulp, suppressing osmotic swelling. Under optimum orthokinetic flocculation conditions of controlled agitation rate and duration, PAM A and PEO-based flocs settled faster than those of PAM N whilst kaolinite pulps produced higher sedimentation rates than smectite pulps. The settling rates are nearly an order of magnitude greater than those observed under standard flocculant–pulp mixing/flocculation methods of inversion and plunging. The difference in the flocculant behaviour is attributed to the more expanded conformation of PAM A and PEO polymer chains in contrast to PAM N, whilst the lower yield stresses, reflecting inter-particle bridging and floc network structure strength that are conducive to faster clarification, were displayed by kaolinite pulps. Following shear, similar consolidation enhancement of ≈ 5–7 wt.% solid for both pulps was achieved at an optimum agitation range of 100–200 rpm. This was accompanied by decreased yield stress in the case of PAM A-based pulps, indicating non-reversible disruption of polymer mediated particle and floc network structure. In contrast, the yield stresses of PAM N and PEO flocculated dispersions indicated similar and stronger particle interactions, respectively, upon consolidation following shear. The findings show clear links between effect of shear, interfacial chemistry and polymer structure on pulp particle interactions and dewaterability.

Consolidation of Syncrude Oil Sands Fine Tailings1

Abstract A novel process has been developed whereby oily sludges produced as an undesirable by-product of bitumen extraction from oil sands can be treated to recover residual organics, heavy metal minerals, and amorphous solids for potential commercial exploitation followed by consolidation of the coarser solids to form wet aggregates. These aggregates may be suitable as fertilizer for fertilizing farmland, making a fertile base for landscaping, or as a natural fertilizer. Introduction The extraction of bitumen from the Athabasca oil sands using the Hot Water Extraction Process results in the accumulation of large volumes of fluid wastes called fine tailings(1, 2). A general description of fine tailings would be a complex system of clays, minerals, and organics. According to Camp(3), fine tailings show little tendency to dewater, even when subjected to mechanical dewatering procedures. These clay tailings are acutely toxic to aquatic organisms and are currently being stored in large tailings ponds. The buildup of these partially settled clay tailings presents not only an environment problem but also a significant repository for non-recyclable water, which eventually must be reclaimed. The reason for the intractability of the clay tailings has been a subject of several studies(4–7). Based on the results of published work, it is generally believed that a combination of residual organics and fine clay particles contribute to the stability of fine tailings. Yong and Sethi(2) have attributed the high water holding capacity of fine tailings to the presence of amorphous minerals such as iron oxide and clays. Our group at NRC has been actively involved in research dealing with various aspects of fine tailings(5–7, 8–14). As a result, we have developed a number of fractionation schemes to separate fine tailings into various components. Recently, we have reported the isolation and characterization of amorphous solids from Syncrude fine tailings(15). In this investigation, we have studied the settling characteristics of fine tailings solids after various treatments. Materials and Methods Materials Aqueous tailings samples used in this investigation were from the Syncrude tailings pond. The physico-chemical properties, handling procedures, and the procedure for the removal of residual bitumen and hydrophobic solids have been reported previously(7). Process Description A flow diagram for the process is shown in Figure 1. The sample is first treated to remove residual bitumen(7, 8). The clean tailings were then divided into two portions. One portion was used to study the consolidation behaviour without removing amorphous solids and the other portion was mixed with one of the reagents to dissolve or disperse amorphous solids(15–17). The contents were agitated until the amorphous solids dissolved producing a dark brown suspension layer. At the end of agitation, the contents were centrifuged for fractionation into a dark brown suspension layer and a sediment layer. The dark brown suspension was carefully decanted from the sediment. This fraction was then treated using the gelation process to precipitate the amorphous solids for potential commercial applications(15). The precipitation of amorphous solids also results in the release of clear water that can be recycled.

Effect of Salt on the Flocculation Behavior of Nano Particles in Oil Sands Fine Tailings

AbstractCurrently, two commercial plants, operating in the Athabasca region of Alberta, produce approximately 20 percent of Canada's petroleum requirements from oil sands. Surface mined oil sand is treated in a water based separation process that yields large volumes of clay tailings with poor settling and compaction characteristics. Clay particles, suspended in the pond water, interact with salts, dissolved from the oil sands ore, to produce mature fine tailings (MFT) containing only 20 to 50 w/w% solids. As a result, large sedimentation ponds are required to produce enough process water to recycle for the plant. Tailings pond dykes can only be constructed during a short summer season. Consequently, the capability to predict production rate and final volume of MFT is essential for mine planning and tailings disposal operations.Previous research has demonstrated that a small fraction of nano sized clay particles (20 to 300 nm) effectively controls the bulk properties of MFT. These particles are present in the original ore and become mobilized into the water phase during the oil separation process. In this work, the nano sized particles have been separated from the bulk tailings and subjected to a fundamental study of their flocculation behavior in model tailings water.Photon correlation spectroscopy and a deuterium NMR method were used to follow particle flocculation and gelation processes. These results were correlated with particle settling data measured under the same conditions. It was determined that the nano particles form fractal flocs that eventually interact to give a thixotropic gel. The ultimate sediment volume produced is almost entirely dependent on the original concentration of nano particles while the rate of water release is governed primarily by electrolyte concentration.

Radium‐226 and Calcium Uptake by Crops Grown in Mixtures of Sand and Clay Tailings from Phosphate Mining

AbstractRadium‐226 is a naturally occurring radionuclide found in reclaimed clay and sand tailings from phosphate mining. Field studies were conducted to investigate the effects of sand/clay ratio (SCR), Ca supplement, and organic amendments on the 226Ra concentration in turnip (Brassica rapa L.), banana pepper (Capsicum annum L.), cabbage (Brassica oleracea var. capitata), yellow squash (Cucurbita pepo L.), mustard [Brassica juncea (L.) Czern & Coss.] and alfalfa (Medicago sativa L.). For vegetables, treatment effects included SCR (2:1, 4:1, 6:1, and 8:1), phosphogypsum (PG) (0, 22, and 134 Mg ha−1), and peat (0, 100, 200 Mg ha−1). For alfalfa grown in a 1:1 SCR mixture, treatments included organic amendments (control, peat, sewage sludge, sawdust, composted sewage sludge, composted garbage and humate) applied at 44.8 Mg ha−1 (2.2 Mg ha−1 for humate). Plant 226Ra concentration tended to be higher in the 4:1 than in the 2:1 SCR mix but this depended on the crop and the season. Organic amendments and PG had no effect (p < 0.05) on the 226Ra concentration in vegetables and alfalfa. Mean 226Ra concentration in plant tissues ranged from 3.4 Bq kg−1 in banana pepper fruit to 31.1 Bq kg−1 in turnip leaf. Sand‐clay mixtures contained 289 to 592 Bq 226Ra kg−1. A quadratic relationship based on 631 observations was observed between 226Ra and Ca concentration in plant tissues. The 226Ra/Ca ratio in plant tissues ranged from 0.85 to 2.13 kBq 226Ra kg−1 Ca and decreased with increasing plant 226Ra. Results indicated that wide differences in plant 226Ca concentration were related more to differences in plant Ca levels than to soil factors.

Migration of acidic pore waters at the Waite Amulet tailings site near Rouyn–Noranda, Quebec, Canada

Pore waters found in the unsaturated zone of the Waite Amulet tailings have been modified by sulphide mineral oxidation, resulting in acidic pH (near 4) and high concentrations of dissolved iron and sulphate at about 5 and 12 g/L, respectively. These pore waters have been displaced down into the shallow saturated zone of the tailings by infiltrating water. Most metals are removed from the pore water as a result of pH buffering before they reach the deeper saturated zone. However, some dissolved metals still remain in solution and are transported with the pore water through the tailings. Numerical flow modelling shows that an anisotropy in hydraulic conductivity (ratio of Kx/Ky is estimated to be 100) exists in the tailings, most likely due to the presence of horizontal fine-grained "slime" layers. The estimated horizontal pore-water velocity is almost 20 times higher than the vertical velocity. Anisotropy in hydraulic conductivity has the effect of promoting horizontal flow over vertical flow in the model. The geometry of the tailings impoundment and the assumed impermeability of the varved clay soil underlying the tailings also contribute to increased horizontal flow. To verify that a preferred horizontal flow exists and that the clay subsoil is indeed impermeable, the geotechnical properties and hydrogeochemistry of the clay are also evaluated. The results indicate that clay located beneath the tailings is slightly overconsolidated in the shallow zone but normally consolidated at greater depth by the weight of the tailings. Overconsolidation ratios reach a maximum value of 2.0. In the clay–tailings interface zone, the soil is characterized by lower in situ water contents and slightly higher undrained shear strengths Cu than the deeper clay. The water contents of the near-interface clay average about 40% and the Cu values 80 kPa, compared with an average water content of 55% and a Cu value of only 20 kPa for the clay at greater depths. These geotechnical properties confirm the presence of a desiccated oxidized upper zone identified in previous studies. It is hypothesized that fractures that could have appeared in the oxidized zone before the tailings deposition would have been closed due to consolidation by the tailings mass. Above-background sulphate concentrations observed in the clay layer at a depth of 1 m are believed to be controlled by diffusion and advection. The presence of fractures in the oxidized zone and excess pore-water pressures generated during consolidation of the clay by the tailings mass could have also influenced chemical transport. Key words : acid generation, acid mine drainage, diffusion, geotechnical, hydrogeochemistry, tailings.

Productivity of Clay Tailings from Phosphate Mining: III. Grain Crops

AbstractPhosphatic clay is a waste product from the Florida phosphate mining industry presently totaling 41 000 ha. These clays contain no phytotoxic materials, are high in most plant nutrients, and 226Ra and average about 460 g moisture per kilogram. A split‐plot field experiment was conducted to study forage and grain yield, forage quality, plant nutrient concentrations, changes in soil nutrients, and 226Ra contents of four grain crops in various rotations. The crop rotations (i) corn (Zea mays L. ‘Jacques 247’)‐sunflower (Helianthus annuus L. ‘Cargill 205’), (ii) sunflower‐grain sorghum (Sorghum bicolor L. Moench ‘Northrup King Savanna 5’), (iii) soybean (Glycine max L. Merr. ‘Williams 80’)‐grain sorghum, and (iv) grain sorghum‐soybean ‘University of Florida V‐1’) were grown on a dry phosphatic clay with and without a 50‐mm surface layer of quartzsand tailings. Nitrogen was the only fertilizer element applied. Results show that corn and grain sorghum produced highest (P < 0.05) forage yields (15.7 and 13.4 Mg ha–1) and highest grain yields (8955 and 4302 kg ha–1) per harvest, respectively. Soybean harvested for forage (Crop 1) contained the highest crude protein (217 g kg–1) and in vitro organic matter digestibility (736 g kg–1). Concentrations of P, K, Ca, Mg, and Fe in most of the forages were adequate for the diets of beef cattle (Bos taunts), while those of Mn, Cu, and Zn were low. Mehlich I‐extractable soil P (1601 mg kg–1), Ca (4696 mg kg–1), and Mg (1173 mg kg–1) were considered very high and changed little over the 4‐yr production period. Application of 50 mm of sand tailings tended to increase (P < 0.05) Mehlich I‐extractable P, Ca, Mn, Cu, Zn, and Fe. Radium‐226 concentration in the forage of all grain crops averaged 8.5 Bq kg–1, which was about 17 times higher than that in the grain (0.4958 Bq kg–1) of the same crops. Concentrations of 226Ra in the forage (8.288 Bq kg–1) and grain (0.6771 Bq kg–1) were 1.1% and 0.09% of the concentration in clay (761 Bq kg–1) respectively. These data indicate that phosphatic clays can be a valuable resource for the production of corn and sorghum grain that contain low concentrations of 226Ra.

Crop Production on Clay Tailings From Phosphate Mining

Crop Production on Clay Tailings From Phosphate Mining

Piezocone tests in a china clay tailings dam : Wakeling, T R M Proc Conference on Penetration Testing in the UK, Birmingham, 6–8 July 1988P167–171. Publ London: Thomas Telford, 1989

Piezocone tests in a china clay tailings dam : Wakeling, T R M Proc Conference on Penetration Testing in the UK, Birmingham, 6–8 July 1988P167–171. Publ London: Thomas Telford, 1989

Productivity of Clay Tailings from Phosphate Mining: II. Forage Crops

AbstractPhosphate mining in Florida produces phosphatic clay and quartz‐sand tailings waste products. Presently there are about 41 000 ha of phosphatic clay (slime ponds) in Florida. These clays contain no phytotoxic materials, are high in most plant nutrients, and average about 460 g moisture kg−1. A split‐plot field experiment was conducted to study forage yield, quality, plant nutrient concentrations, changes in soil nutrients, and 226Ra contents of 12 grass‐N source treatments. The treatment combinations (i) bahiagrass (Paspalum notatum Fluegge var. saurae Parodi ‘Pensacola’) + N, (ii) bahiagrass + white clover (WC) (Trifolium repens L. ‘Arcadia’), (iii) stargrass (Cynodon nlemfuensis Vanderyst var. nlemfuensis ‘Florico’) + N, (iv) Florico stargrass + WC, (v) Florico stargrass + alfalfa (Medicago sativa L. ‘Florida 77’), (vi) Florico stargrass + carpon desmodium (Desmodium heterocarpon (L.) D.C. ‘Florida’), (vii) Limpograss [Hemarthria altissima (Poir) Stapf et. C.E. Hubb. ‘Floralta’] + N, (viii) Limpograss + WC, (ix) Stargrass (C. nlemfuensis Vanderyst var. nlemfuensis ‘Florona’) + N., (x) Florona stargrass + WC, (xi) Florona stargrass + red clover (Trifolium pratense L. ‘Nolins’), and (xii) Florona stargrass + alfalfa, were grown on dry phosphatic clay with and without a 50 mm surface layer of quartz‐sand tailings. Nitrogen (500 kg ha−1 yr−1) was the only fertilizer element applied on grasses. No fertilizer was applied on legumes during the 4‐yr period. Results indicated that Floralta hemarthria + N, Florona stargrass + N, and Florona stargrass + alfalfa produced highest dry‐forage yields averaging 20.8, 18.1, and 17.7 Mg ha−1. Florico stargrass + WC and Floralta hemarthria + WC had annual averages of 233 and 211 g CP kg−1 and 769 and 751 g IVOMD kg−1, respectively. Grass + N treatments were about 5 to 10 percentage units lower in CP than grass + legumes. Forage mineral concentrations for P, K, Ca, Mg, Mn, Cu, Zn, and Fe, ranged from 1.3 to 39 times higher than required for growing and finishing cattle (Bos sp.). Mehlich I‐extractable soil P (1650 mg kg−1), Ca (4588 mg kg−1), and Mg (1130 mg kg−1) were very high and changed little after 4 yr of forage production. Forages had a differential uptake of 226Ra with Florona stargrass + N (1.28 pCi g−1) having the highest uptake and Pensacola bahiagrass + N (0.32 pCi g−1) having the lowest uptake. Radium 226 in the phosphatic clay was 22 pCi g−1, which was 80 times higher than levels in an unmined Spodosol; however, plant uptake was three times higher than plants grown on unmined soil. Data indicated that phosphatic clays are a fertile resource that can be used for forage production.