Valorisation diagnosis of waste from the decontamination of phosphogypsum leachates through a combined calcium carbonate/hydroxide process.

Phosphogypsum is an industrial waste considered as naturally occurring radioactive material. Stack disposal and exposure to the environmental condition involve the production of acid leachates with high potential pollutant loads as heavy metals and radionuclides. In this study, a sequential neutralisation process was applied for cleaning the generated releases, and the two obtained residues were characterised from the physical-chemical and radiological point of view before their valorisation. The cleaning process was made up of two steps: the first one using calcium carbonate until pH = 3.5, and the second one using calcium hydroxide until pH = 12. The residue obtained in the first step was mostly calcium fluoride, while in the second step most phosphates were precipitated, mainly as hydroxyapatite. The final liquid was treated to reduce pH lower than 9, which is the limit included in the current directive for discharges of liquid effluents into coastal waters. The main conclusion was that the solids from the first step could be valorised as an additive in the manufacture of commercial Portland cements and ceramics, while the solids from the second step could be used as raw material for the phosphoric acid manufacture.

[Oral lichen planus: epidemiological observations in Argentina]. / Liquen plano bucal: observaciones epidemiológicas en Argentina.

The prevalence of the oral lichen planus and its distribution by sex, age and clinical forms was studied in population's samples and series of cases. The prevalence rates observed ranged from 0.129 to 0.38% with the highest values (0.66%) in the oldests groups of age. In the series of cases no significant differences were observed in sex distributions with increased values of prevalence, in both sexes, over 40 years of age and the highest values in the fifth decade of life. Atypical clinical forms, specially erosive forms, predominated in the series of cases but not in the population samples. Their true occurrence must be establish by epidemiological works on wider samples of people.

Liquen plano bucal: observaciones epidemiológicas en Argentina / [Oral lichen planus: epidemiological observations in Argentina]

The prevalence of the oral lichen planus and its distribution by sex, age and clinical forms was studied in population’s samples and series of cases. The prevalence rates observed ranged from 0.129 to 0.38

with the highest values (0.66

) in the oldests groups of age. In the series of cases no significant differences were observed in sex distributions with increased values of prevalence, in both sexes, over 40 years of age and the highest values in the fifth decade of life. Atypical clinical forms, specially erosive forms, predominated in the series of cases but not in the population samples. Their true occurrence must be establish by epidemiological works on wider samples of people.