Daiane Calheiro

Review of the rice production cycle: By-products and the main applications focusing on rice husk combustion and ash recycling:

One of the consequences of industrial food production activities is the generation of high volumes of waste, whose disposal can be problematic, since it occupies large spaces, and when poorly managed can pose environmental and health risks for the population. The rice industry is an important activity and generates large quantities of waste. The main solid wastes generated in the rice production cycle include straw, husk, ash, bran and broken rice. As such, the aim of this article is to present a review of this cycle, the waste generated and the identification of opportunities to use them. Owing to impacts that can be minimised with the application of rice husk ash as a by-product, this work is focused on the recycling of the main wastes. In order to achieve that, we performed theoretical research about the rice production cycle and its wastes. The findings point to the existence of an environmentally suitable use for all wastes from the rice production cycle. As rice, bran and broken rice have their main use in the food industry, the other wastes are highly studied in order to find solutions instead of landfilling. Straw can be used for burning or animal feeding. The husk can be used for poultry farming, composting or burning. In the case of burning, it has been used as biomass to power reactors to generate thermal or electrical energy. This process generates rice husk ash, which shows potential to be used as a by-product in many different applications, but not yet consolidated.

Comparison between Rice Husk Ash and Commercial Silica as Filler in Polymeric Composites

The use of rice husk ash (RHA) as filler in polymeric materials has been studied in different polymers. Research reported that RHA may successfully replace silica. The silica production process using ore demands high energy input and produces considerable amounts of waste. Therefore, the replacement of silica by RHA may be economically and environmentally advantageous, reducing environmental impact and adding value to a waste material. In this context, this study characterizes and compares RHA of different sources (moving grate and fluidized bed reactor) with commercially available silicas to assess performance as filler in polymeric materials. Samples were characterized by X-ray fluorescence, loss on ignition, X-ray diffraction, grain size, specific surface area, specific weight, and scanning electron microscopy. The results show that RHA may be used as a filler in several polymeric materials.

Influência da segregação granulométrica e do emprego de aditivos de moagem na adequação de cinzas de casca de arroz como coproduto

A cinza de casca de arroz (CCA) e um residuo proveniente da combustao da casca de arroz utilizada como biomassa na producao de energia. Esta cinza e gerada em grandes quantidades e possui baixa massa especifica, o que dificulta o seu gerenciamento, pois demanda muito espaco para o devido armazenamento e descarte. A CCA possui um elevado teor de silica em sua composicao, fator este que pode torna-la um material atrativo para varios segmentos industriais. Neste contexto, este trabalho tem como objetivo avaliar a influencia do beneficiamento fisico da cinza de casca de arroz, por meio de processos de segregacao granulometrica e moagem, com e sem o uso de aditivos, nas caracteristicas deste material e na sua adequacao como coproduto. A metodologia experimental utilizada para o desenvolvimento deste trabalho envolveu a segregacao e moagem da CCA (com e sem aditivos de moagem), caracterizacao quimica, fisica e estrutural das amostras de CCA bruta, segregadas e moidas. Os resultados obtidos indicam que a segregacao granulometrica se apresenta como fator determinante para a utilizacao da CCA como coproduto. Com relacao a moagem, pode-se verificar que o diâmetro medio das particulas diminui e a massa especifica das amostras aumenta, com o aumento do tempo de moagem. Entretanto, verifica-se que os aditivos usados neste trabalho, nas concentracoes testadas, nao influenciam significativamente na reducao do diâmetro das particulas.

Adaptation of Rice Husk Ash for Use as Pozzolanic Material

The use of waste in the construction industry is an interesting approach to minimize associated environmental impacts. A substantial body of research has proved the potential use of rice husk ash (RHA) as a mineral additive. A considerable portion of RHA presents pozzolanic characteristics, a result of its amorphous chemical structure and high silica contents. However, variations in particle size and chemical composition may affect applicability, limiting the use of RHA. In this scenario, this study presents a methodology to recycle RHA based on particle segregation and discusses how the process affects RHA performance in terms of its pozzolanic activity. Samples and respective segregated fractions were characterized using physical (loss on ignition, specific weight, surface area, grain size distribution), chemical (chemical composition and X-ray diffraction) and microstructural (scanning electron microscopy and energy dispersion) parameters. Pozzolanic activity was determined after milling of samples and segregation of fractions based on specific assays with cement and on electric conductivity. The results show that segregation opens new perspectives to increase the value of RHA in the construction industry.