Two types of industrial hypereutectic Fe-C-Si alloys, with carbon saturation index as a measure of their eutecticity, SC = 1.11 and SC = 1.18, show “anomalous” behavior during their solidification processes for 3 out of 5 alloys. In order to determine their cause, behavior of their liquid cooling before solidification is analyzed through their parameters: thermal history [T-t], cooling rate [(dT/dt)L-t] and loss of heat content rate [(dQ/dt)L-t]. Simultaneous evaluation of them let us associate to the metallurgical concept of Liquid Metal Constitution (LMC) as the cause for such “anomalous” behavior, due to LMC affects the formation of phases during solidification for any type of alloys. Unetched macrostructures around thermocouple placement for the five alloys specimens solidified at cooling rates in the range of 6-8 ºC/s in precooked sand molds, demonstrate all of them are gra...

Polvos de acería residuales, provenientes de una siderúrgica venezolana, se caracterizaron fisicoquímicamente, detectándose que los mismos poseían elevados contenidos de metales pesados como Fe, Zn y Pb y un elevado pH de contacto, superior a 12 unidades, lo que lo convierte en un residuo peligroso por su tendencia a generar lixiviados con elevada alcalinidad. Debido a estos resultados, se planteó un proceso de remediación del residuo mediante lavados secuenciales con soluciones diluidas de (CH2)2COH(COOH)3 (ácido cítrico), (COOH)2 (ácido oxálico), CH3COOH (ácido acético) y H2SO4 (ácido sulfúrico). Se obtuvo que la solución de CH3COOH generó la mayor atenuación de la alcalinidad de los polvos, llegando los mismos a acidificarse hasta un pH de alrededor de 4 unidades.

Two types of industrial hypereutectic Fe-C-Si alloys, with carbon saturation index as a measure of their eutecticity, SC = 1.11 and SC = 1.18, show “anomalous” behavior during their solidification processes for 3 out of 5 alloys. In order to determine their cause, behavior of their liquid cooling before solidification is analyzed through their parameters: thermal history [T-t], cooling rate [(dT/dt)L-t] and loss of heat content rate [(dQ/dt)L-t]. Simultaneous evaluation of them let us associate to the metallurgical concept of Liquid Metal Constitution (LMC) as the cause for such “anomalous” behavior, due to LMC affects the formation of phases during solidification for any type of alloys. Unetched macrostructures around thermocouple placement for the five alloys specimens solidified at cooling rates in the range of 6-8 ºC/s in precooked sand molds, demonstrate all of them are gra...

Residual steelmaking powders, coming from a Venezuelan steel mill, were characterized physicochemically, detecting that they had high contents of heavy metals such as Fe, Zn and Pb and a high pH of contact, greater than 12 units, which makes it a waste dangerous due to its tendency to generate leachates with high alkalinity. Due to these results, a remediation process of the residue was proposed through sequential washes with dilute solutions of (CH2) 2COH (COOH) 3 (citric acid), (COOH) 2 (oxalic acid), CH3COOH (acetic acid) and H2SO4 ( sulfuric acid). It was obtained that the CH3COOH solution generated the greatest attenuation of the alkalinity of the powders, reaching acidity until a pH of around 4 units.