Granulation of nanocomposites based on glauconite and urea: binding materials and characterization of activated mineral fertilisers

Relevance. Development of controlled release fertilisers and their granulation is at the forefront of agriculture and environment. With growing world population and increasing food demand, agriculture faces the challenge of efficient resource management and increased crop yields. In this environmentally friendly and easy to obtain and use fertilisers become a key element for sustainable development of agribusinesses. Aim. To study the complete cycle of creation of granular fertilisers based on new materials, including aggregation of mineral particles with different binding solutions and mechanochemical activation of initial mixtures of glauconite and urea. Potassium-containing clay mineral – glauconite of Karinskiy deposit (Russia) was used as a "container" material. Urea containing up to 46 wt % of nitrogen was used as an additive (nutrient) component for fertilisers. The following parameters were stable during mechanochemical preparation: mineral/urea ratio and abrasion type. Solutions with different nitrogen concentrations were used as binders during granulation. The methodology for investigating the characteristics of the resulting nanocomposites included particle size analysis, X-ray diffraction analysis, scanning electron microscopy, and FTIR spectrometer. Results. The advantages of different granulation options for mechanochemically activated composites were investigated. The authors have produced f full cycle of controlled-release granular fertiliser. The average nitrogen content in glauconite particles reaches 5.5 wt %. The granule size depends on the content of urea gel concentrate in the binder. The maximum strength and proportionality of granules are achieved, when using a binder consisting of 100% urea gel concentrate. Determination of the optimal content of gel concentrate in the binder used in granulation plays a key role in obtaining strong fertiliser granules

Preparation, features, and efficiency of nanocomposite fertilisers based on glauconite and ammonium dihydrogen phosphate

This paper studies the chemical and mechanochemical preparation of glauconite with ammonium dihydrogen phosphate (ADP) nanocomposites with a ratio of 9:1 in the vol.% and wt.%, respectively. The methods include X-ray diffraction analysis, scanning electron microscope with energy-dispersive X-ray spectroscopy, transmission electron microscopy, infrared spectroscopy, and differential thermal analysis with a quadruple mass spectrometer. The manufactured nanocomposites keep the flaky glauconite structure. Some glauconite unit structures have been thickened due to minimal nitrogen (ammonium) intercalation into the interlayer space. The globular, granular, or pellet mineral particles of nanocomposites can be preserved via chemical techniques. Globular and micro-aggregate particles in nanocomposites comprise a thin film of adsorbed ADP. The two-step mechanochemical method makes it possible to slightly increase the proportion of adsorbed (up to 3.2%) and intercalated (up to 6.0%) nutrients versus chemical ways. Nanocomposites prepared via chemical methods consist of glauconite (90%), adsorbed (1.8–3.6%), and intercalated (3.0–3.7%) substances of ADP. Through the use of a potassium-containing clay mineral as an inhibitor, nitrogen, phosphorus, and potassium (NPK), nanocomposite fertilisers of controlled action were obtained. Targeted and controlled release of nutrients such as phosphate, ammonium, and potassium are expected due to various forms of nutrients on the surface, in the micropores, and in the interlayer space of glauconite. This is confirmed via the stepwise dynamics of the release of ammonium, nitrate, potassium, and phosphate from their created nanocomposites. These features of nanocomposites contribute to the stimulation of plant growth and development when fertilisers are applied to the soi

Characterisation and Environmental Significance of Glauconite from Mining Waste of the Egorievsk Phosphorite Deposit

This article presents the results of a study of glauconite obtained from phosphate rock waste. The aim is to study the morphological, structural and chemical characteristics of glauconite and to determine the potential for secondary use of mining waste in the agricultural sector. The electromagnetic separation method was used to obtain glauconite concentrate. The optimum parameters for obtaining the maximum mineral content in the concentrate were determined. Studies have shown that glauconite is characterised by globular, granular grains of the highly mature variety. Glauconite almost invariably contains inclusions of pyrite and apatite, which significantly improve the characteristics of the fertiliser. Laboratory experiments have shown that glauconite waste and glauconite concentrate have a positive effect on plant growth and development. The high potassium content, the favourable globular shape of the grains, and the presence of apatite and pyrite inclusions indicate the potential use of glauconite from mining waste as a potash fertiliser. Application of glauconite fertiliser to the soil will provide an opportunity to improve its texture, providing better moisture and aeration. The use of glauconite fertiliser is particularly valuable on acidic soils where apatite can be dissolved, making phosphorus available to plants. This nutrient additionally favours plant growth, as well as reducing the risk of heavy metal accumulation in the soil. Thus, glauconite from the waste of the Egorievsk deposit represents a promising fertiliser for improving soil quality and increasing crop yields

Intercalation of carbamide to globular glauconite by chemical processing for the creation of slow-release nanocomposites

This article investigates the intercalation of carbamide within globular glauconite involving the chemical activation of glauconite with carbamide solution-gel at varying concentrations of total nitrogen (N). Mineral nanocomposites were prepared with a multitude of novel functions. As the N concentration of the initial solution increased, the proportion of intercalated N enhanced to 8%. A 20% of N concentration in carbamide solution maximizes intercalation. Intercalation occurs in the interlayer of smectite layers (micropores) in glauconite. In nanocomposites, the decrease in specific surface space, total volume pores, and average pore size reflect the absorption of carbamide in meso- and macropores of glauconite globules. Glauconite nanocomposites retain a spherical particle morphology and a distinct microlayer close to the surface. The increased proportion of nitrogen in the microlayers close to the surface indicates a high filtration capacity of the globules. The near-surface microlayer serves as a diffusion channel for the glauconite interior, where new substances are absorbed in the micro- (interlayer) and macropores. The stepwise kinetics of nutrient release, which supports the various forms of carbamide absorption in glauconite, distinguishes the nanocomposites. In addition to N-compounds, glauconite nanocomposites are mineral sources of the available potassium (K) in soils. As a result, chemically manufactured glauconite nanocomposites have some following advantages: the micro-granular mineral form, a permeable inner near-surface microlayer, incubated in micro-, meso-, and macropores N-compounds, and the available K