Production at Kiviõli Keemiatööstus is divided into three main sections:
The thermal processing of oil shale produces shale oil, phenols and lower calorific value gas.
Processing is done using two technologies:
Kiviter (a generator device) technology is based on vertical cylindrical retorts in which the shale oil in fixed grain size (25-125 mm) used as input moves by the force of gravity along the central section of the retort. To deplete the organic matter of oil shale, hot smoke gas, which is obtained from burning the shale oil gas in another section of the same retort, is guided through the shale oil layer. The oil steam and lower calorific value pyrolysis gas resulting from the process are led into the condensation system.
The solid heat carrier (TSK) uses a horizontal rotating cylindrical retort in which fine grain (up to 25 mm) oil shale is used and where the thermal depletion of organic matter is obtained by mixing the hot oil shale ashes directly with the oil shale. The process results in oil steam and higher calorific value gas.
The parallel use of the two technologies allows for greater flexibility in raw material use; the oil shale fraction sized 0-125 mm is used, at the same time, the finer fraction of raw material shifted from the Kiviter process can be used in the solid heat carrier process.
Phenols are separated from the pyrolysis product from the oil production and are sold as products for further processing.
Five steam boilers and two turbo generators operate in the heat and electricity production unit. The company also supplies thermal energy for the town of Kiviõli.
Kiviõli Keemiatööstus uses oil shale, pyrolysis gas and shale oil for combined heat and power production. The thermal energy is used in the shale oil production process and is also sold to the local district heating network operator for sale to consumers.
The company’s thermal power station is not oriented only to combined heat and power production; its main task is to utilise the pyrolysis gas instead of emitting it into the air and receive the thermal and electric energy from burning the gas. The amount of pyrolysis gas emitted during shale oil production is constant throughout the year. To utilise this, more electric energy must be produced during the summertime low heat consumption period and more thermal energy during the wintertime high consumption period.
Mining and quarrying
The company mines shale oil in the North Kiviõli II shale oil quarry, where selective quarrying without ore enrichment is used in heavy suspension. Selective quarrying is executed with the help of Wirtgen SM 2500 surface miner and modern Komatsu bulldozers, excavators and loaders.
Mining is divided into stages. The first stage is preparation, which involves planning and preparatory works such as deforestation and water removal. Works follow involving bulldozers, where the soft top cover and soil are removed. The latter is stored separately in piles for restructuring. After the soft layer is removed, the rocky layer (limestone) is broken either mechanically or, if necessary, using drilling and explosives. The oil shale is then selectively mined (oil shale layers are extracted separately from the limestone). The extracted mineral is crushed and screened. The resulting technological shale oil with a grain size of 25-125 mm is used in the generator device, fine oil shale with a grain size of 0-25 mm is used in the solid heat carrier or sold to other energy companies. After the oil shale is mined, restructuring works divided into technological and biological tasks are conducted. During the technological restructuring, the open casts created by mining are evened and the surface is prepared for biological restructuring. Biological restructuring mainly involves reforestation according to the restructuring project.
In addition to oil shale mining, the company possesses two mining permits for gravel quarries: the Moldova gravel quarry and the Kolustre gravel quarry.