Evaluation of red sludge use efficiency for water purification from sulphates

In this work the reagent purification of aqueous solutions from sulfates with the use of red sludge of the Nikolaev alumina plant processes were investigated. This sludge, according to chemical analysis, contains a sufficiently large amount of alumina (up to 18 %) and calcium oxide (up to 10 %) and along with calcium silicate and iron oxides contains sodium and calcium aluminates. The ability of sodium aluminate to be deposited from a solution of sulfates in the form of calcium sulfoaluminates was used in the work to purify water from sulfate anions. The process takes place when treating the solution with sludge and lime suspension. It is shown that when red sludge is applied in the amount of 1–50 g/dm3 during magnesium sulfate solutions liming, water is purified from sulfate anions. The degree of water purification reaches 50–70 %. It was found that the efficiency of sulfate extraction is significantly dependent on the consumption of lime and increases slightly with increasing sludge consumption over 1 g/dm3. The dependence of the efficiency of sulfate extraction from water on their initial concentration is determined. It was found that at the initial concentration of sulfates up to 1000 mg/dm3 at the expense of lime 3–12 mg-eq/dm3 the residual concentration of sulfates decreases to 236–460 mg/dm3, and at the concentration of sulfate anions about 2000 mg/dm3 their concentration decreases to 550–830 mg/dm3 at a lime consumption of 30 mg-eq/dm3 regardless of the sludge consumption. The degree of extraction of sulfates from solutions reaches 40–73 %.

Direct microalloying of structural steels by boron from oxide system CaO–SiO2–B2O3–Al2O3–MgO

The results of fundamental studies of the physicochemical properties of slags of the CaO–SiO2–B2O3–Al2O3–MgO system were used as the basis for the development of the technology for the formation of boron-containing slags in ladle-furnace units (LFU). The recommended composition of ladle slags (1–4% B2O3, 15% Al2O3 and 8% MgO) ensures the development of direct microalloying processes of steel with boron, low viscosity, not exceeding 0.32 Pa∙s, and preservation of sufficiently high refining properties. Colemanite (Turkey) was used as boron-containing raw material, having, %: 39–41 B2O3, 26–28 CaO, no more than 5% of SiO2 and 3% of MgO. The implementation of the developed technology of direct microalloying of structural steels of a wide grade composition by boron in the BOF shop of ArcelorMittal Temirtau JSC provided the boron content at the level of 0.001–0.008%, a decrease in the consumption of manganese-based ferroalloys from 0.3 kg/t of 08кп steel to 0.8 kg/t of steel 17Г1С-У, exclusion of additives into the ladle of ferroboron and fluorspar. The proposed mode of formation of slags of the recommended composition in the melt of LFU provided a sufficiently high degree of metal desulfurization in comparison with the existing production routes. For example, with pipe steel 17Г1С-У, despite a decrease in lime consumption by 500 kg per a heat and a decrease of the steel processing time at the LFU by 40 minutes, a high degree of desulfurization, reaching 66.7%, provided a sulfur content of 0.004% in the metal. Microalloying of structural steels by boron results in their high strength properties with invariance of plasticity apart from sufficiently high refining effect.

Impact of tops and green leaves on sugarcane processing: laboratory testing

In Réunion, changes in harvesting practices have led to increased amounts of sugarcane tops and leaves delivered to factories. To anticipate the changes in sugar recovery processing, laboratory trials were undertaken. Samples with known quantities of tops or green leaves were prepared and cane processing was simulated at laboratory scale: juice extraction, clarification and evaporation with operating parameters similar to those in the factory. Juice and syrup were collected and analyzed for sugar quality parameters, as well as parameters that impact sugar recovery or processing quality: ash and reducing sugars contents were monitored to estimate the sucrose loss to molasses, while calcium, phosphate and oxalate contents were monitored to evaluate the risk of fouling in evaporator. Results highlight a degradation of juice composition with increasing quantities of tops and leaves, an increase in lime consumption, and color. An increase in residual calcium in syrup was observed thus increasing the risk of evaporator fouling. The mixed juice, clear juice and syrup qualities declined in the same proportion and the composition of the juice did not get worse with juice treatment.

A System Dynamics Model for Sales and Operations Planning

The use of system dynamics techniques to model the sales and operations planning (S&OP), associated with the economic and financial processes, is an innovative proposal. The objectives of this article are to model and simulate the S&OP process integrated with the financial management in a Brazilian lime processing industry, based on the system dynamics approach. Initially, the model was validated. Then, over twenty scenarios were simulated to assess the behavior of the system with its key factors variation. In the microenvironment scenarios, the company's internal perspective was the only element taken into account. In turn, regarding the macro environment scenarios, the basis was the projection of lime consumption related to the country's GDP. The results have genuinely contributed to the industry researched, since the lime processing industry is struggling with obtaining enough supply due to lime acquisition price fluctuations and, consequently, the oscillation of its production costs.

Effect of Lime and Organic Binders on Clay Gold-Bearing Ores Filterability

The present work relates to hydrometallurgy, in particular, to gold-bearing clay ores leaching processes. The initial and agglomerated material filterability was studied. Filterability varies in different agglomeration conditions. Influence of cement, lignosulfonate, plastizer (Cemmix CemPlast), lime consumption was investigated. The negative effect of organic reagents additives, such as plasticizer (Cemmix CemPlast) and lignosulfonate, on the filtration process was established. Colmatation of agglomerated ore minimizes at CaO and Ca (OH)2 using as a modifier of the system, also phase separation in the percolation regime and under pressure proceeds without difficulty. Lime and cement joint use in the optimum proportion at clay ore agglomeration under the studied conditions reduces the filtration duration from a few hours to 2-5 minutes.

PREHISPANIC MAYA BURNT LIME INDUSTRIES: PREVIOUS STUDIES AND FUTURE DIRECTIONS

Burnt lime has played a significant role in daily Maya life since at least as far back as 1100 b.c., and yet its ephemeral nature has limited archaeological studies of its production. The application of new surveying and remote sensing technologies in recent decades is now allowing for a more in-depth investigation of the burnt lime industries that existed in different subregions of the Maya area. This article provides an overview of the current understanding of pre-Hispanic Maya burnt lime production. It then presents an analysis of the factors influencing the development and identification of distinct subregional lime production industries, including: lime consumption requirements and inter-site spacing; natural environment; local social and economic trajectories; and the objectives and survey universes of archaeological investigations. In reporting the tremendous advances made over the past few decades, this paper encourages archaeologists to include a focus on identifying lime production features in their research agendas.