Recovery from tar sand

Flotation or froth flotation is a physicochemical property-based separation process. It is widely utilised in the area of mineral processing also known as ore dressing and mineral beneftciation for mineral concentration. In addition to the mining and metallurgical industries, flotation also finds appHcations in sewage treatment, water purification, bitumen recovery from tar sands, and coal desulfurization. Nearly one biUion tons of ore are treated by this process aimuaHy in the world. Phosphate rock, precious metals, lead, zinc, copper, molybdenum, and tin-containing ores as well as coal are treated routinely by this process some flotation plants treat 200,000 tons of ore per day (see Mineral recovery and processing). Various aspects of flotation theory and practice have been treated in books and reviews (1 9). 

Doscher, T. M. et al., Oil Recovery from Tar Sands, Canadian patent... 

In situ bitumen recovery from tar sands promises to have a lower environmental impact than surface mining and extraction. Water recovered with the bitumen from steam drive in situ tar sands processing requires treatment before reuse or discharge. 

Petroleum refining, also called petroleum processing, is the recovery and/or generation of usable or salable fractions and products from cmde oil, either by distillation or by chemical reaction of the cmde oil constituents under the effects of heat and pressure. Synthetic cmde oil, produced from tar sand (oil sand) bitumen, and heavier oils are also used as feedstocks in some refineries. Heavy oil conversion (1), as practiced in many refineries, does not fall into the category of synthetic fuels (syncmde) production. In terms of Hquid fuels from coal and other carbonaceous feedstocks, such as oil shale (qv), the concept of a synthetic fuels industry has diminished over the past several years as being uneconomical in light of current petroleum prices. 

Petroleum Recovery. Steam is iajected iato oil wells for tertiary petroleum recovery. Steam pumped iato the partly depleted oil reservoirs through iaput wells decreases the viscosity of cmde oil trapped ia the porous rock of a reservoir, displaces the cmde, and maintains the pressure needed to push the oil toward the production well (see Petroleum, enhanced recovery). Steam is also used ia hot-water extractioa of oil from tar sands (qv) ia the caustic conditioning before the separatioa ia a flotatioa tank (35). 

In a general sense, however, the term heavy oil is often appHed to a petroleum that has a gravity <20° API. The term heavy oil has also been arbitrarily used to describe both the heavy oil that requires thermal stimulation for recovery from the reservoir and the bitumen in bituminous sand (also known as tar sand or oil sand) formations, from which the heavy bituminous material is recovered by a mining operation. Extra heavy oil is the subcategory of petroleum that occurs in the near-soHd state and is incapable of free flow under ambient conditions. The bitumen from tar sand deposits is often classified as an extra heavy oil. 

In principle, the nonmining recovery of bitumen from tar sand deposits is an enhanced oil recovery technique and requires the injection of a fluid into the formation through an injection weU. This leads to the in situ displacement of the bitumen from the reservoir and bitumen production at the surface through an egress (production) weU. There are, however, several serious constraints that are particularly important and relate to the bulk properties of the tar sand and the bitumen. In fact, both recovery by fluid injection and the serious constraints on it must be considered in toto in the context of bitumen recovery by nonmining techniques (see PETROLEUM, ENHANCED OIL RECOVERY). 

SADEGHIET AL. Surfactant Vesicles from Tar Sand Recovery... 

Two options for the recovery of oil from tar sands are of importance mining of the tar sands, followed by aboveground bitumen extraction and upgrading and in situ extraction, in which the bitumen is released underground by thermal and/or chemical means and then brought to the surface for processing or upgrading. Because the processes of in situ recovery are similar to those employed in the enhanced recovery of crude oil, they are not discussed. 

To exemplify the problems of demulsification of oil, some steps in the recovery of bituminous oil from tar sands are considered. The Great Canadian Oil Sands, Ltd. (GCOS) Process has been described in various... 

Late in 1975, personnel from Laramie Energy Research Center (LERC), then of the U.S. Energy Research and Development Administration, conducted an in situ recovery experiment in the Northwest Asphalt Ridge deposit near Vernal, Utah. Reverse combustion was chosen as a recovery method because it was felt that this method was more likely to succeed for in situ recovery of tar sands hydrocarbons. 

In this way the useful petroleum fractions are recovered from the surface or near surface exposures of tar sand by the two currently operating hot water process extraction plants in Alberta. The production of synthetic crude oil by Alberta tar sand processors has risen from 28 million barrels (ca. 4 million tonnes) in 1978, to 77.3 million barrels (ca. 10.5 million tonnes) in 2003, which now supplies about 13% of Canada s current crude oil requirements [48]. Other processes for bitumen recovery from minable sands, such as preliminary partial sand removal with the help of cold water, followed by direct coking of the whole of the bitumen/solid residue, and solvent extraction methods have both been tested but are apparently not attractive for commercial development [49]. 

Thermal Recovery of Oil from Tar Sands by an Energy-Efficient Process... 

In all thermal recovery processes, tar sand is subjected to high processing temperatures, about 450-550°C for pyrolysis, and the residual coked sand is further heated to about 550-650°C during the combustion step. At these conditions, an acceptable thermal efficiency can only be obtained if a significant portion of the sensible heat in the spent sand is recovered and introduced back into the process. Almost all the processes in Table I provide for heat recovery from spent sand before it is discarded. 

The process permits recovery of oil from tar sands with high energy efficiency in a once-through operation with respect to sand. 

Jayakar, K. M., "Thermal Recovery of Oil from Tar Sands," Ph.D. Thesis in Chemical Engineering, University of Utah (1979). 

Schramm, L.L. (1988) Use of a submersible viscometer in the primary separation step of the hot water process for recovery of bitumen from tar sand, Canadian Patent 1,232,854, Feb. 16,... 

The worldwide base for oil from tar sands has not been well determined. For the Athabasca tar sands in Alberta, Canada, where cotmnercial recovery has been pursned for more than 25 years, a resource value of 625 x 10 bbl was estimated by Spragins (1967) and corresponds to... 

The viscosities of crude oil found in these sands are typically high because of low temperature and recovery from these sands will require enhanced oil recovery (EOR) technology. Based on the EOR screening, miscible and thermal processes are considered to be suitable for recovery of crude from West Sak sands, while only thermal processes are considered to be applicable for recovery of Ugnu tar sands. The unconsolidated and friable sands also pose problems in well completion and production. 

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