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The magnesium leaching was studied experimentally in ammoniacal carbonate solution, of the lateritic ore processed in the reduction furnaces of the nickel-producing plant in Nicaro, Cuba, in order to determine the effect of ammonia concentration, ammonia - carbon dioxide ratio, temperature and the free magnesium content, over reaction kinetics and liquor supersaturation concentration. The ore was taken in the discharge of the rotary coolers in an inert atmosphere; and the liquor was prepared with distilled water, NH4OH solution and ammoniacal-carbonate Fresh Liquor. It was obtained that by increasing the concentration of ammonia from 60 to 80 g/L and decreasing the NH3/CO2 ratio from 2,0 to 1,5 in the leaching liquor, at the temperature of 42 ° C, the magnesium supersaturation concentration decreased because of the zero-order leaching resulting rate increased, leading nucleation, and in turn the first-order precipitation rate increased; while increasing the temperature from 42 to 54 °C, to 60 g/L of NH3 and NH3/CO2 ratio equal to 1,8, there was an adverse effect to the process, the leaching rate increased, the precipitation rate decreased and augmented supersaturation concentration from 409 to 600 mg/L. The lower the free magnesium content in the reduced mineral, the lower the magnesium dissolved concentration in the leaching liquor. [ABSTRACT FROM AUTHOR]

In present work, the heat transfer coefficients and the incrustation factor of the cane juice are determined. Measurements are made, as well as inlet and outlet temperatures of cane juice and steam. The heat transfer global coefficients are determinate and compared with the literature criteria for the estimation of the incrustation regime. Its application in "Siboney" plant, allows to obtain levels of coefficient reduction of 42% and 50% for the heat exchanger A and B, respectively, in 15 days of operation. [ABSTRACT FROM AUTHOR]

Heat exchangers' fouling causes increased resistance to thermal exchange, with subsequent efficiency loss. Although related analysis has been exposed in previous studies, the available mathematical models do not consider all forms and mechanisms of deposition of unwanted material. This investigation proposed two models for prediction of the fouling thermal resistance in a system of hydrogen sulphide gas coolers under operations. The values for independent and response variables inherent to the process were obtained by applying the passive experimentation method. Correlations of 98,07 % and 97,23 % were achieved from the multivariable regression model (for the tubeside-shellside heat exchange and the shellside-jacket interaction, respectively), as compared to 99,63 and 99,03 % for the artificial neural network. The results confirm the validity of both techniques as reliable forecasting tools, with the neural network being the best predictor. [ABSTRACT FROM AUTHOR]

The sulphide acid coolers are tube and shell jacketed heat exchangers designed to cool down the produced gas from 416,15 K to 310,15 K in addition to separate the sulphur carried over by the outlet gas from the reactor tower. The investigation was carried out by applying the passive experimentation process in an online cooler set in order to determine the heat transfer rates and fouling based on heat resistance. It was corroborated that the operation of this equipment outside design parameters increases outlet gas temperature and liquid sulphur carryovers. Efficiency loss is caused by fouling elements in the fluid, which results in changes in the overall heat transfer rate. The linear tendency of the fouling heat resistance based on time for three gas flowrates. [ABSTRACT FROM AUTHOR]

This paper deals with the evaluation of magnetic treatment effect in boiler feeding water for avoiding formation of inlays and negative corrosion effects. This work is developed in Siboney sugar mill, in Camaguey, Cuba. Magnetic treatment effectiveness is demonstrated, because of useful life of exposed metallic surfaces is increased and corrosion effects decreased. It is proved because there was slight deposition in form of a fine send. Kinetic parameters and inlay characterization show in all cases significant when implementing hypothesis test. This result permits to save energy as well as fuel and provides a very important environmental effect. [ABSTRACT FROM AUTHOR]

In this work it was carried out a systematizing abaut the different factors influencing in the magnesium leaching in ammonio amoniacal carbonate liquors. There were related the insoluble complex compounds formed, causing of inlays. The reduction temperature effect and the mineral composition on the formation of free or amorphous magnesium were analyzed. For simple lineal regression a directly proportional relationship was obtained among the increment of the magnesium in the fed mineral and the free or amorphous magnesium formed in the reduced mineral to oneself temperature of reduction of 750°C, with a correlation coefficient of 0,9699 and standard error, 0,18. [ABSTRACT FROM AUTHOR]

After a brief description of hard water process, a current information about the anti-scaling magnetic technology on heat exchanger systems is widely given. The main hypothesis or mechanisms that are likely to account for all of the observed industrial effects, as well as some of the experimental results given by leading researchers on this subject are outlined. Authentic examples in some factories from industrialized countries are presented to show up why magnetic treatment technology is displacing the chemical treatment as a second option. [ABSTRACT FROM AUTHOR]