Process and apparatus for improving raw tobacco

A process for improving tobacco raw material by conducting extraction from tobacco raw material used in cigarette industry with solvent, removing harmful components and backfilling with the feed liquid to obtain the improved tobacco raw material, wherein the process comprises the following steps:

• 1) mixing more than one of tobacco raw materials selected from tobacco leaves, flakes, cuts tobacco, tobacco powder, stalks, and cut stems with a mixed solvent containing 65˜97% of purified water and 3˜35% of other solvents at a mass ratio of 1:4˜30 between tobacco raw material and the solvent, conducting extraction at a temperature of 10˜80° C. for a period of 1˜120 min;
• 2) conducting solid-liquid separation for the tobacco raw material after extraction by means of squeezing or centrifugation until the dryness of tobacco raw material reaches 20˜60%;
• 3) preparing extract of natural tobacco to be used in the process from the extracted liquor after the solid-liquid separation of the tobacco leaves, flakes or cuts, the extracted liquor after the solid-liquid separation of the stalks or the cut stems being used for producing fertilizer but not in the process;
• 4) preparing the backfilling feed liquid by the following steps:
• firstly, diluting 1˜10 parts by mass of aqueous extract of natural tobacco and 0.1˜15 parts by mass of alcohol extract of natural tobacco and mixing the dilution uniformly, secondly, removing harmful components, and lastly, forming the backfilling feed liquid with a concentration controlled by 20˜50%;
• 5) adjusting the dryness of the tobacco raw material after the solid-liquid separation to 40˜60%, then backfilling uniformly the backfilling feed liquid to the tobacco raw material after solid-liquid separation by spraying or immersion, with a mass ratio of the backfilling being 10˜420%;
• and
• 6) drying the tobacco raw material backfilled with the feed liquid until the moisture thereof reaches 11˜13% to obtain the end product.