Centro Azúcar Journal

TECHNOLOGIES FOR OBTAINING MANGANESE SULFATE FROM MINERALS ADAPTED TO THE CUBAN CONTEXT

Lisandra Guevara Orozco, Nicole Vieira Ribalta, Néstor Ley Chong — Mon, 11 May 2026 00:00:00 +0000

Introduction:
Manganese sulfate (MnSO₄) is a compound of high commercial value, essential for the production of agricultural fertilizers. In Cuba, there is availability of manganese-bearing minerals, as well as a growing need to develop domestic inputs for the agro-industrial sector.
Objective:
To analyze the main technological routes for producing MnSO₄ from minerals, and evaluate their possible adaptation to the Cuban context.
Materials and Methods:
A bibliographic review was conducted using databases such as ScienceDirect and google scholar. Analysis–synthesis and induction–deduction methods were applied to process information on minerals, metallurgical processes, and operational variables.
Results and Discussion:
Pyrolusite was identified as the most relevant oxidized mineral and is abundant in Cuban deposits. A comparative analysis of technological routes showed that hydrometallurgy, through acid leaching with reducing agents, is the most promising alternative due to its high efficiency, selectivity, lower energy requirements, and flexibility for small and medium scales. Critical process variables and various reducing agents were analyzed. The use of organic reductants, such as sawdust available locally as an agro-industrial by-product, emerges as an economically and environmentally attractive alternative.
Conclusions:
The hydrometallurgical route, using reducing agents of national origin, represents the most viable technological alternative for manganese sulfate production in Cuba, enabling the use of national mineral resources and promoting sustainable industrial development.

ALUMINOTHERMIC OBTAINING OF IRON ALLOY AND CERAMIC USING MILL SCALE AS THE MAIN RAW MATERIAL

Mon, 11 May 2026 00:00:00 +0000

Introduction:
Mill scale is an industrial waste generated during the hot rolling of steel, representing approximately 2 % of the produced steel. In Cuba, it is generated by companies like Antillana de Acero and Acinox Las Tunas and is currently underutilized.
Objective:
To obtain iron alloys and refractory ceramics through aluminothermic processing using lamination scale as the fundamental raw material.
Materials and Methods:
A McLean Anderson experimental design was used, varying the proportions of mill scale, aluminum chips, and limestone. Seven charges were prepared and processed in a graphite reactor to obtain the corresponding alloys and ceramics.
Results and Discussion:
The resulting alloys contained carbon (0.3 – 0.67 %), silicon (0.3 – 1.61 %), manganese (0.1 – 0.96 %), and aluminum (0.25 – 1.88 %), with a metal recovery rate of 73 – 91 %. The ceramics, composed mainly of aluminum and iron oxides, showed a recovery rate of 93 – 110 %.
Conclusions:
The results demonstrate the technical feasibility of the process. This method allows for obtaining iron alloys for industrial use and ceramics suitable for developing abrasive and refractory materials. The proposal represents a viable solution for valorizing this waste, contributing to environmental preservation.

EFFECT OF STEP-BY-STEP MASHING TO IMPROVE THE SENSORY PROFILE OF CRAFT BEER

Mon, 11 May 2026 00:00:00 +0000

Introduction:
The research analyzes stepped maceration applied at different successive temperatures as a strategy to optimize the extraction of compounds that influence the physicochemical and sensory quality of craft beer. This method allows for modulation of enzymatic activity during the brewing process, which could impact the composition of the wort and the final characteristics of the product.
Objective:
To evaluate the effect of stepped maceration on the physicochemical and sensory properties of craft beer by applying three mashing temperatures (65 °C, 70 °C, and 75 °C) with variations in exposure times, analyzing their influence on the final density and sensory attributes.
Materials and Methods:
Wort was produced under three thermal regimes (65 °C, 70 °C, and 75 °C) with variable residence times. Physicochemical analyses included pH, density, titratable acidity, °Brix, and turbidity, along with microbiological controls to ensure product safety. Sensory evaluation was conducted through comparative tests using a trained panel. The data were analyzed using ANOVA and Turkey's test.
Results and Discussion:
The commercial beer achieved a higher overall score (2.55) than the experimental sample (2.18). This discrepancy was attributed to the presence of astringent notes and pronounced acidity in the stepped sample, suggesting that extraction efficiency alone does not necessarily ensure sensory quality.
Conclusions:
Stepped maceration improves physicochemical parameters; however, further adjustments are necessary to achieve an appropriate sensory balance.

IN VITRO INTERACTION BETWEEN TRICHODERMA HARZIANUM RIFAI LBMA 34 AND METARHIZIUM ANISOPLIAE LBMA 11

Mon, 11 May 2026 00:00:00 +0000

Introduction:
Agriculture faces challenges such as excessive pesticide use and pest resistance, making it necessary to employ innovative alternatives such as biological control agents to ensure its sustainability and productivity.
Objective:
To evaluate the in vitro behavior of the growth of the fungus Trichoderma harzianum LBMa 34 against Metarhizium anisopliae LBMa 11.
Materials and Methods:
The distance at which the fungi faced each other was measured, using distances of 2, 4, and 6 cm on an 8.5 cm plate. Radial growth between them and separately was measured, and the quality parameters corresponding to concentration, viability, and purity were determined.
Results and Discussion:
Trichoderma harzianum LBMa 34 grows faster than Metarhizium anisopliae LBMa 11 by 1.8 mm/day. Both maintain similar quality parameters, and the greater distance between them (6 cm) favors the development and expansion of M. anisopliae by reducing competition.
Conclusions:
Trichoderma harzianum LBMa 34 exhibits faster growth than Metarhizium anisopliae LBMa 11, although the latter is significantly favored by greater spatial separation (6 cm vs 2 cm), which reduces competition and allows for rapid establishment.

VANADIUM RECOVERY FROM SPENT CATALYSTS: A TECHNICAL, ENVIRONMENTAL, AND ECONOMIC SOLUTION FOR CUBA

Mon, 11 May 2026 00:00:00 +0000

Introduction:
Catalytic residues generated in the production of sulfuric acid in Cuba contain vanadium, a metal classified as critical and without natural deposits in the country, which represents an environmental and economic problem. These polluting residues are stored in unsafe conditions or confined in facilities with limited capacity, which makes it necessary to seek sustainable solutions.
Objective:
To present the technical, economic, and environmental considerations regarding the recovery of vanadium contained in catalytic waste from sulfuric acid production.
Materials and Methods:
At Universidad Central “Marta Abreu” de Las Villas, a technological process has been developed based on crushing, acid leaching, filtration, precipitation, and calcination, using domestic reagents.
Results and Discussion:
The result is a concentrate with 37.8% V₂O₅, which can be marketed or transformed into ferrovanadium for the manufacture of recharge electrodes, an industrial input that Cuba currently imports at high cost. The research shows that processing these catalysts makes it possible to convert hazardous waste into a strategic raw material, reducing dependence on the international market and applying principles of circular economy and cleaner production. Alternatives are proposed for utilizing the solid and liquid by-products obtained, minimizing the generation of new waste.
Conclusions:
From a social and economic point of view, the proposal would contribute to import substitution, the strengthening of national industry, and environmental sustainability, while also generating a positive impact on strategic sectors, integrating science, innovation, and sustainable development in Cuba.

EVALUATION OF SUGAR CANE BAGASSE ASH AS A DEVELOPING POWDER FOR FINGERPRINT DETECTION

Mon, 11 May 2026 00:00:00 +0000

Introduction:
The recovery of latent fingerprints is fundamental in criminal investigations. The search for effective, safe, and low-cost developing is a priority.
Objective:
To evaluate the quality of sugarcane bagasse ash (SBA) as a latent fingerprint developing powder using a comprehensive methodology that considers physicochemical, practical, and efficacy parameters.
Materials and Methods:
SBA was characterized through physical (density, porosity) and chemical (XRF) analysis. Its performance as a developer was evaluated using an adapted methodology that included technical verification, performance characterization under controlled conditions, and pseudo-operational validation, comparing it to a reference standard.
Results and Discussion:
SBA presented an apparent density of 0.341 g/cm³, a porosity of 66.95 %, and a specific surface area of 11.79 m²/g. Its predominant chemical composition, expressed as oxides, was SiO₂ (43.55 %), K₂O (18.49 %), P₂O₅ (12.85 %), SO₃ (10.05 %), CaO (6.67 %), and MgO (6.12 %). In development tests, it showed high adhesion and contrast, with an Effective Development Rate (EDR) exceeding 80 % on glass and stainless steel, without generating false positives. Its performance was statistically equivalent to the standard in pseudo-operational tests.
Conclusions:
Sugarcane bagasse ash is a viable, effective, and sustainable fingerprint developing powder. Its quality is demonstrated through a comprehensive scientific evaluation, and its incorporation into Cuban criminalistics protocols is recommended.

APPLICATION OF EXPERIMENTAL PLANS FOR THE DETERMINATION OF OPTIMAL INVESTMENT CAPACITIES IN THE DAIRY INDUSTRY

Sun, 10 May 2026 00:00:00 +0000

Introduction:
There are no technologies in Villa Clara for utilizing the cream from fresh milk; there is only one facility in the province equipped with such technology.
Objective:
To determine the optimal investment capacities for skimming and processing fresh milk in Villa Clara.
Materials and Methods:
Evaluate, using saturated factorial designs, the possibilities of utilizing the cream contained in fresh milk at the pasteurization plants of Santa Clara and Sagua, employing cost per unit of weight produced as the optimization parameter.
Results and Discussion:
The inclusion of investments in fresh milk skimming lines and butter production in Sagua and Santa Clara showed a decrease in cost per unit weight, through previously non-existent capacities that are recovered in one year.
Conclusions:
The combination of economic analysis and experimental designs offers a robust framework for evaluating technological and economic alternatives.

PROCEDURE FOR EQUIPMENT LAYOUT IN A CHEMICAL PLANT WITH INFRASTRUCTURE CONSTRAINTS

Mon, 11 May 2026 00:00:00 +0000

Introduction:
The layout of equipment in existing chemical plants directly influences operating costs, as material transport has a direct impact on operating expenses. Optimizing these material flows in facilities with pre-existing infrastructure constraints requires specific methodological approaches.
Objective:
To propose a structured heuristic procedure for the reconfiguration and placement of equipment in existing chemical plants.
Materials and Methods:
A six-step procedure was designed based on analyses of technical documents and systematic site visits.
Results and Discussion:
The procedure allows for the identification of bottlenecks and redundant routes in operating plants, facilitates decision-making, and overcomes the limitations of ideal theoretical models that are not applicable to rigid infrastructures.
Conclusions:
The procedure provides a structured framework for equipment layout in existing plants, enabling improvements without large-scale investments in chemical industry facilities.