The paper provides information about phosphogypsum waste from various enterprises and how it can be used in the production of slow-release fertilizer mixtures. Such fertilizer mixes can potentially be used with different types of soil, including acidified soils. Experiments were conducted on phosphogypsum samples from the old and new dumpsites under the Taraz branch of Kazphosphate LLP. All representative samples underwent chemical, mineralogical, thermal gravimetric and differential thermal analyses, as well as Fourier-Transform Infrared (FTIR) spectroscopy and polarized optical microscopy (POM). No significant differences were found in the content of the samples. Phosphogypsum from the old dumpsite contained 87.93% gypsum (CaSO 4 • 2H 2 O), 9.10% quartz (SiO2), 17.55% calcium (Ca), 0.13% potassium (K), 0.35% phosphorus (P), and 0.80% phosphorus pentoxide (P2O5). Phosphogypsum from the new dumpsite contained 85.04% gypsum, 10.58% quartz (SiO2), 19.42% calcium (Ca), 0.14% potassium (K), 0.30% phosphorus (P), and 0.69% phosphorus pentoxide (P2O5). The current paper also offers a technological scheme for making a slow-release fertilizer mixture with phosphogypsum.
The article presents the results of a study of the corrosion properties of oxide coatings compacted with polymers and without compaction. Oxide coatings were obtained on VT1-0 and VT5 titanium alloys under the influence of fast pulsed actions of the micro-arc oxidation (MAO) process. To form MAO coatings, a pulsed mode of the process was used with an anodic current pulse duration of 250 ± 25 μs; the cathodic current pulse duration of 5 ± 0.5 ms; pause between anodic and cathodic current pulses 250 ± 25 μs; repetition rate of anodic and cathodic pulses 50 ± 0.5 Hz. Alkaline solutions were used as electrolytes. Fluoroplastic and epoxy resin solutions were used to seal the oxide coatings. The obtained MAO coatings have 4.4 – 7.5 % porosity on the VT1-0 alloy and 5.4 – 12.1 % on the VT5 alloy. The average diameter of oxide coating pores varies from 0.1 to 0,5 µm. X-ray phase analysis showed titanium dioxide in anatase and rutile modification in the oxide coatings composition. Tests performed in a 24 % solution of sulfuric acid at 40 and 75°C showed that the coatings on the VT1-0 alloy, both oxide and oxide-polymer, are more corrosion resistant than similar coatings on the VT5 alloy. All types of coatings produced on VT1-0 alloy are corrosion-resistant at a test temperature of 40 °C. Consolidation of MAO coatings with polymeric materials improves corrosion properties.
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