scholarly journals Phosphogypsum recycling into inorganic dyes

2019 ◽  
Vol 140 ◽  
pp. 01002
Author(s):  
Nina Shabelskaya ◽  
Roman Medvedev ◽  
Yuliya Gaidukova ◽  
Marina Astachova
Keyword(s):  
Citric Acid ◽  
Phosphoric Acid ◽  
Acid Production ◽  
Calcium Sulfate ◽  
Uv Light ◽  
Raw Materials ◽  
Reducing Agents ◽  
Calcium Sulfide ◽  
Secondary Products ◽  
Main Component

Currently, chemical wastes recycling into valuable secondary products poses a pressing challenge. During phosphoric acid production from apatite raw materials, large-tonnage phosphogypsum wastes are formed, resulting in ecosystem dysfunction. Besides, such wastes occupy significant production areas. Calcium sulfate is the main component of phosphogypsum. The paper addresses the possibility of phosphogypsum reduction to calcium sulfide, which has the capacity for luminescence under UV-light. Charcoal, sucrose, and citric acid were used as reducing agents. The obtained inorganic luminescent dyes were examined using X-ray phase analysis, scanning electron microscopy (SEM), and electron probe microanalysis (EPMA). It was found that, in the presence of charcoal, the process is accompanied by an uneven distribution of calcium sulfide over the volume of the system and, as a consequence, an uneven glow of the sample. The use of citric acid and sucrose as reducing agents results in the synthesis of samples with a uniform glow. The efficiency of the calcium sulfate conversion to calcium sulfide is 51–58%. A mechanism of calcium sulfate reduction is proposed. The obtained results can serve as a basis for the development of a technology for the recycling of large-tonnage phosphoric acid production wastes into cheap and much-needed inorganic luminescent dyes.

scholarly journals Simple superphosphate by two-stage acid treatment of phosphate raw materials

2021 ◽  
Vol 939 (1) ◽  
pp. 012057
Author(s):  
D Sherkuziev
Keyword(s):  
Phosphoric Acid ◽  
Flow Rate ◽  
Acid Treatment ◽  
Calcium Sulfate ◽  
Raw Materials ◽  
Production Cycle ◽  
Second Stage ◽  
Additional Input ◽  
Concentrated Solution ◽  
Two Stages

Abstract The distinguishing feature of the proposed flow method before the classical (chamber) method is that the entire production cycle of natural phosphate processing is carried out in two stages. At the first stage, the phosphorite is treated with a stoichiometric flow rate of concentrated sulphuric acid (at least 93%), under conditions of complete decomposition of phosphorite to form phosphoric acid and crystals of anhydrite (calcium sulfate). The reaction temperature is 122 °C. In the second stage, the resulting concentrated solution of phosphoric acid in a mixture with sulphur is involved in a reaction with an additional input of phosphorite, which is the basis for the mechanism of chemical formation of monocalciumphosphate and granulation of superphosphate mass. The processes for neutralizing phosphoric acid on monocalciumphosphate and for granulating the product by coagulation are combined in one apparatus. The drying stage of the product is excluded from the scheme.

The Effect of Zinc on the Portland Cement Hydration

2018 ◽  
Vol 761 ◽  
pp. 131-134 ◽  
Author(s):  
Pavel Šiler ◽  
Iva Kolářová ◽  
Jiří Másilko ◽  
Radoslav Novotný ◽  
Tomáš Opravil
Keyword(s):  
Mechanical Properties ◽  
Portland Cement ◽  
Rotary Kiln ◽  
Cement Hydration ◽  
Raw Materials ◽  
Cement Industry ◽  
Secondary Products ◽  
Secondary Raw Materials ◽  
Main Component ◽  
Portland Cement Hydration

Concrete is still the most commonly used building material. The main component of concrete is Portland cement. Due to increasing use of secondary products containing zinc, the amount of zinc in the clinker or in the secondary raw materials is increasing in recent years. Portland clinker can gain zinc from solid waste or tires which are widely used as a fuel for a burning in rotary kiln. In the case of secondary raw materials, zinc may be present in the primary material, where the manufacturing process leads to its removal and concentrating to "waste" which is used in the cement industry. The biggest problem with cement doped with zinc is the retardation of hydration and decreasing of mechanical properties. The main aim of this work is describing and evaluation of zinc effect on the course of Portland cement hydration.

Characterization of Hydroxyapatite Synthesized from Calcium Hydroxide and Phosphoric Acid as Adsorbents of Lead in Wastewater

2020 ◽  
Vol 991 ◽  
pp. 159-165
Author(s):  
Nguyen Hoc Thang ◽  
Phong Thanh Dang
Keyword(s):  
Phosphoric Acid ◽  
Calcium Hydroxide ◽  
Raw Materials ◽  
Calcium Hydroxyapatite ◽  
X Ray Diffraction ◽  
X Ray ◽  
Physico Chemical ◽  
Bet Analysis ◽  
Main Component

Calcium hydroxyapatite (also known as hydroxyapatite - HA), formula Ca5(PO4)3(OH) or Ca10(PO4)6(OH)2, is a double salt of tri - calcium phosphate and calcium hydroxide. And apatite exists naturally in the form of fluorine-apatite Ca10(PO4)6F2. In human and animal body, HA is the main component in bone (accounting for 65-70% weight) and teeth (99%). In this study, calcium hydroxide (Ca(OH)2) and phosphoric acid (H3PO4) were used as raw materials to produce hydroxyapatite (HA). The hydroxyapatite was synthesized by hydrothermal method. Physico-chemical and microstructural properties of the HA were characterized by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), Brunnaeur-Emmett- Teller (BET) analysis and Scanning Electron Microscope (SEM) and compared with standard sample of HA. For lead treatment in wastewater, adsorption of HA was tested by measuring concentration of lead of the adsorption process. In which, Pb is one of the toxicity heavy metals that caused many dangerous diseases and threatening human health and life.

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