Briquetting of wastes from coffee plants conducted in zero harvest system

Abstract

The briquetting process consists of lignocellulosic residues densification in solid biofuel with high calorific value denominated briquette. Coffee crop is one of the most important Brazilian commodities and according to the cultural practices produces plant residues in different amounts. The zero harvest system in coffee crop is based in pruning of plagiotropic branches in alternated years to make possible to concentrate the harvest and to avoid coffee biannual production. The aim of the present work was to verify the viability of briquette production using the biomass waste obtained by zero harvest system. The treatments were composed of briquetting process: 1) coffee rind; 2) mixture of branches and leaves; 3) 25% of coffee rind + 75% of branches and leaves; 4) 75% of coffee rind + 25% of branches and leaves; 5) 50% of coffee rind + 50% of branches and leaves; 6) 40% of coffee rind + 60% of branches and leaves. The mixtures were realized in v/v base, milled to produce 5-10 mm particles and were briqueted with 12% of humidity. The C-teor of briquettes produced ranged from 41.85 to 43. 84% and sulphur teor was below 0.1%. The calorific value of briquettes produced ranged from 3,359 to 4, 028 Kcal/ kg and the ashes were below 6%. The isolated use of coffee rind or branches and leaves, as well the mixtures of coffee rind with 50% or more of branches and leaves allow the production of briquettes with calorific value around 4,000 Kcal/ kg which is within the quality parameters. The briquetting of coffee crop wastes is viable and sustainable energetically.