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Previous issue date: 2012-06-15 === Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior === During the process of the salt production, the first the salt crystals formed are
disposed of as industrial waste. This waste is formed basically by gypsum, composed of
calcium sulfate dihydrate (CaSO4.2H2O), known as carago cru or malacacheta . After be
submitted the process of calcination to produce gypsum (CaSO4.0,5H2O), can be made
possible its application in cement industry. This work aims to optimize the time and
temperature for the process of calcination of the gypsum (carago) for get beta plaster
according to the specifications of the norms of civil construction. The experiments involved
the chemical and mineralogical characterization of the gypsum (carago) from the crystallizers,
and of the plaster that is produced in the salt industry located in Mossor?, through the
following techniques: x-ray diffraction (XRD), x-ray fluorescence (FRX), thermogravimetric
analysis (TG/DTG) and scanning electron microscopy (SEM) with EDS. For optimization of
time and temperature of the process of calcination was used the planning three factorial with
levels with response surfaces of compressive mechanical tests and setting time, according
norms NBR-13207: Plasters for civil construction and x-ray diffraction of plasters (carago)
beta obtained in calcination. The STATISTICA software 7.0 was used for the calculations to
relate the experimental data for a statistical model. The process for optimization of calcination
of gypsum (carago) occurred in the temperature range from 120? C to 160? C and the time in
the range of 90 to 210 minutes in the oven at atmospheric pressure, it was found that with the
increase of values of temperature of 160? C and time calcination of 210 minutes to get the
results of tests of resistance to compression with values above 10 MPa which conform to the
standard required (> 8.40) and that the X-ray diffractograms the predominance of the phase
of hemidrato beta, getting a beta plaster of good quality and which is in accordance with the
norms in force, giving a by-product of the salt industry employability in civil construction === Durante o processo de produ??o do sal, os primeiros cristais formados s?o
descartados como res?duo industrial. Esse res?duo ? constitu?do basicamente por gipsita,
composto de sulfato de c?lcio di-hidratado (CaSO4.2H2O), conhecido como carago cru ou
malacacheta . Ap?s ser submetida a processo de calcina??o para obten??o do gesso
(CaSO4.0,5H2O) , pode ser viabilizada a sua aplica??o na ind?stria cimenteira. Este trabalho
tem como objetivo otimizar o tempo e a temperatura para o processo de calcina??o da gipsita
(carago) para obten??o do gesso beta de acordo com as especifica??es da norma da
constru??o civil. Os experimentos envolveram a caracteriza??o qu?mica e mineral?gica da
gipsita (carago) oriunda dos cristalizadores, e do gesso que ? produzido na ind?stria salineira
localizada em Mossor?, atrav?s das seguintes t?cnicas: difra??o de raios-X (DRX),
fluoresc?ncia de raios X (FRX), an?lise Termogravim?trica (TG/DTG) e a microscopia
eletr?nica de varredura (MEV) com EDS. Para otimiza??o do tempo e temperatura do
processo de calcina??o foi utilizado o planejamento fatorial de tr?s n?veis com superf?cies de
respostas dos ensaios mec?nicos de resist?ncia ? compress?o e tempo de pega conforme a
norma NBR-13207: Gessos para Constru??o civil e a difra??o de raios-X dos gessos (carago)
beta obtidos na calcina??o. O software STATISTICA 7.0 foi usado para os
c?lculos para relacionar os dados experimentais para um modelo estat?stico. O processo para
otimiza??o da calcina??o da gipsita (carago) ocorreram na faixa de temperatura de 120?C a
160?C e o tempo na faixa de 90 a 210 minutos no forno a press?o atmosf?rica, verificou-se
que com o aumento dos valores da temperatura de 160?C e no tempo de calcina??o para 210
minutos obtemos resultados dos ensaios de resist?ncia a compress?o com valores acima de 10
MPa que est?o de acordo com o requerido pela norma (>8,40) e que nos difratogramas de
raios- X temos a predomin?ncia da fase do hemidrato beta, obtendo um gesso beta de boa
qualidade e que est? de acordo com as normas vigentes, dando a um subproduto da ind?stria
salineira a empregabilidade na constru??o civil
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