The Effect of Water Vapor on the Thermal Decomposition of Pyrite in N2 Atmosphere

Abstract

In this study, the effect of water vapor on the thermal decomposition of pyrite mineral in nitrogen atmosphere has been investigated in a horizontal tube furnace. Temperature, time and water vapor concentration were used as experimental parameters. According to the data obtained at nitrogen/ water vapor environment, it was observed that the water vapor on the decomposition of pyrite increased the decomposition rate. The decomposition reaction is well represented by the "shrinking core" model and can be divided into two regions with different rate controlling step. The rate controlling steps were determined from the heat transfer through the gas film for the low conversions, while it was determined from the mass transfer through product ash layer for the high conversions. The activation energies of this gas and ash film mechanisms were found to be 77 and 81 kJ/mol-1, respectively.

Keywords

• Pyrite, Thermal decomposition, Water vapor, Shrinking core model.

Piritin N2 Atmosferinde Isıl Bozunmasına Su Buharının Etkisi

Öz

Bu çalışmada pirit mineralinin azot atmosferinde ısıl bozunması üzerine su buharının etkisi yatay bir boru fırın içinde incelendi. Deneysel parametreler olarak sıcaklık, zaman ve su buharı konsantrasyonu kullanıldı. Azot/su buharı ortamında elde edilen verilere göre, piritin bozunması üzerine su buharının bozunma hızını arttırdığı gözlemlendi. Bozunma reaksiyonunun, "büzülen çekirdek modeli" ile iyi uyum sağladığı ve farklı hız kontrol basamaklı iki bölgeye ayrıldığı belirlendi. Hız kontrol basamakları, düşük dönüşümlerde akışkan filminden ısı transfer kontrollü, yüksek dönüşümlerde ise kül filminden difüzyon kontrollü olduğu tespit edildi. Bu gaz ve kül filmi mekanizmalarının aktivasyon enerjileri sırası ile 77 ve 81 kJ/mol-1 olarak bulundu.

Anahtar Kelimeler

• Pirit, Isıl bozunma, Su buharı, Büzülen çekirdek modeli

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