The preparation of ferrous sulfate from pyrite cinder by reduction roasting method 用熟化法从硫铁矿烧渣中提取铁
2.
Specialty coffees are generally roasted in small batches . the two most common roasting methods are : drum - roasting and hot - air roasting 专业的咖啡一般都实行小批量的烘焙。最常见的烘焙方法有：鼓室烘焙法和热空气烘焙法。
