Cementation primary

The process described so far is called a primary cementation, the main purpose of which is to ... 

Sometimes primary cementations are not successful, for instance if the cement volume has been wrongly calculated, if cement is lost into the formation or if the cement has been contaminated with drilling fluids. In this case a remedial or secondary cementation is required. This may necessitate the perforation of the casing a given depth and the pumping of cement through the perforations. 

Table 3 Hsts the characteristics of CAC mineral constituents that can occur in CAC of varying purities. The primary hydraulic setting cement phase in all CAC grades is CA [12042-68-1/, CaO AI2O2 the main secondary phase in 70% AI2O2 CAC is Ca2, [12004-88-5] CaO 2AI2O2. CA2 and C 2 ...

The first equation is an example of hydrolysis and is commonly referred to as chemical precipitation. The separation is effective because of the differences in solubiUty products of the copper(II) and iron(III) hydroxides. The second equation is known as reductive precipitation and is an example of an electrochemical reaction. The use of more electropositive metals to effect reductive precipitation is known as cementation. Precipitation is used to separate impurities from a metal in solution such as iron from copper (eq. 1), or it can be used to remove the primary metal, copper, from solution (eq. 2). Precipitation is commonly practiced for the separation of small quantities of metals from large volumes of water, such as from industrial waste processes. 

Plastic cements are hydrauHc cements that have plastici2ing agents added to Pordand cement during the grinding operation to make them dow better. The primary use for plastic cements is in plasters and stucco. 

Cemented carbide iaserts and tools for metal-cutting and metal-working have traditionally accounted for the largest percentage of carbide iadustry sales. However, carbide tool consumption ia nonmetal-working fields, notably ia the constmction and transportation iadustries, has grown rapidly. On the other hand, the demand for primary materials has been somewhat reduced by use of recycled cemented carbide scrap. 

A number of cemented carbide producers market some or all primary materials, ranging from monocarbides to binary or ternary soHd solutions involving TiC, TaC, NbC, or WC. Among the suppHers offering these materials are Keimametal Inc., GTE Products Corp., Teledyne Wah Chang, and Tokyo Tungsten Co. Ltd. Keimametal Inc, also manufactures TiN and TiCN powders. 

Further reduction in the price of carbon fibers may enable penetration into the automotive market. A primary carbon fiber producer has armounced that prices will drop to 700 yen/kg ( 6.80/lb) by 1995 (73) and that cooperative development efforts with a main Japanese automobile producer are underway. Development for use in constmction, such as cement and cable reinforcement, and marine apphcations will result in sustained growth volume through the eady twenty-first century. 

Concern with regard to energy conservation has prompted the use of byproduct materials ia Portland cement concrete. Blended hydrauHc cements are produced by intimately and uniformly blending two or more types of fine materials. The primary blending materials are Portland cement, ground... 

Coal was the primary kiln fuel in 1989 as seen in Table 10. Energy from coal rose from 39 to 84% of the total energy required for cement production between 1972 and 1989. In the same time period, natural gas dropped to 9%, petroleum products to 1% of the total energy consumed. Waste fuels represented 5% of the energy consumed in 1989 cement production. 

In the past 30 years, the ready-mixed concrete industry became the primary customer for cement manufacturers. In 1990 more than 72% of the cement shipped was sold to the ready-mixed concrete industry, compared with 63% in 1975. The other primary uses are in building materials, concrete products, and highway constmction. 

Coal-cleaning plants (with thermal dryers) Kraft-pulp mills Portland-cement plants Primary zinc smelters Iron and steel mill plants Primary aluminum-ore-reduction plants Primary copper smelters ... 

Cement plants Quarrying primary crusher, secondary crusher, conveying, storage Particulates (dust) Wetting exhaust systems with fabric filters... 

Particulate matter emissions are the primary concern with cement manufacture. Fugitive emissions and uncontrolled kiln emissions are shown in Table 30-23. 

Erst-, first, initial, original, primary, erstarren, v.t. solidify, congeal, freeze (of cement, etc.) set harden coagulate become stiff or torpid. 

In addition to primary cementing of the casing and liner, there are other important well cementing operations. These are squeeze cementing and plug cementing Such operations are often called secondary or remedial cementing [161]. 

There are two basic oil well cementing activities primary cementing and secondary cementing. 

Primary cementing refers to the necessity to fix the steel casing or liner (which is placed in the drilled borehole) to the surrounding formations adjacent to the casing or liner. The purposes of primary cementing are the following ... 

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