The oil extracted from the sands in the northeast corner of alberta begins as bitumen , a thick and sulfurous heavy-oil precursor , and the costs of mining and processing it are immense .
About 80 % of the oil sands are deep underground and extracted by injecting steam to soften the bitumen and then separating it from the sand before pumping it above ground .
An increasing amount of the oil supplied is bitumen from the oil sands , which continues to bear an expensive environmental and economic cost per barrel under current technology .
越来越多的石油被用于从油砂中提炼沥青,在目前技术下,此举将继续付出昂贵的环境和经济代价。
Environmentalists , so vocal about canada 's tar sands ( see article ) , have so far been silent over venezuela 's bitumen .
过去曾高声抗议加拿大(参见:加拿大石油)提炼焦油砂的环保人士,迄今对于委内瑞拉提炼沥青仍静默观望。
By adding rubber " crumbs " , reclaimed from shredded tyres , to the bitumen and crushed stone used to make asphalt , engineers are designing quieter streets .
在沥青和碎石里添加从轮胎碎片中回收的废胶末,再铺成柏油路,这样工程师可以设计出更加安静的街道。
In alberta , canada , a host of companies are scouring vast deposits of oil sands for bitumen , a molasses-like substance that can be converted-through energy-intensive processes-into refinable crude oil .
Just last month someone used a bulldozer and ploweda two-foot-deep gash in the desert , unearthing the brick and bitumen remains of a stairway possibly leading to another cemetery .
He dissolved the bitumen in lavender oil , a solvent often used in varnishes , and coated the sheet of pewter with this light capturing mixture , he placed the sheet inside a camera obscura to capture the picture , and eight hours later removed it and washed it with lavender oil to remove the unexposed bitumen .