S content

Triple (Concentrated) Superphosphate. The first important use of phosphoric acid in fertilizer processing was in the production of triple superphosphate (TSP), sometimes called concentrated superphosphate. Basically, the production process for this material is the same as that for normal superphosphate, except that the reactants are phosphate rock and phosphoric acid instead of phosphate rock and sulfuric acid. The phosphoric acid, like sulfuric acid, solubilizes the rock and, in addition, contributes its own content of soluble phosphoms. The result is triple superphosphate of 45—47% P2 s content as compared to 16—20% P2 5 normal superphosphate. Although triple superphosphate has been known almost as long as normal superphosphate, it did not reach commercial importance until the late 1940s, when commercial supply of acid became available. 

In addition to the indicated total world reserves of about 21 x 10 t having P2 s content of at least 30%, and the 9.1 x 10 ° t classified as resources, there are about 250 x 10 t of reserves and resources derived from guano which are not included in Table 14. 

Modem commercial wet-acid purification processes (see Fig. 4) are based on solvents such as C to Cg alcohols, ethers, ketones, amines, and phosphate esters (10—12). Organic-phase extraction of phosphoric acid is accompHshed in one or more extraction columns or, less frequently, in a series of countercurrent mixer—settlers. Generally, 60—75% of the feed acid P2 s content is extracted into the organic phase as H PO. The residual phosphoric acid phase (raffinate), containing 25—40% of the original P2O5 value, is typically used for fertilizer manufacture such as triple superphosphate. For this reason, wet-acid purification units are almost always located within or next to fertilizer complexes. 

At equihbrium, the specific composition of a concentrated phosphoric acid is a function of its P2 s content. Phosphoric acid solutions up to a concentration equivalent of about 94% H PO (68% P2O5) contain H PO as the only phosphoric acid species present. At higher concentrations, the orthophosphoric acid undergoes condensation (polymerization by dehydration) to yield a mixture of phosphoric acid species (Table 5), often referred to genericaHy as polyphosphoric or superphosphoric acid, H20/P20 = - 3, or ultraphosphoric acid, H20/P20 = - 1. At the theoretical P2O5 concentration for orthophosphoric acid of 72.4%, the solution is actually a mixture containing 13% pyrophosphoric acid and about 1% free water. Because the pyrophosphoric acid present is the result of an equihbrium state dependent on the P2 5 content of the solution, pure orthophosphoric acid can be obtained because of a shift in equihbrium back to H PO upon crystallization. 

Cooling is ordinarily too rapid to maintain the phase equiHbria. In the case ia Figure 1, the lime-deficient Hquid at 1455°C requires that some of the soHd C S redissolve and that more C2S crystallise duting crystallisation of the C A. During rapid cooling there may be iasufficient time for this reaction and the C S content is thus higher than when equiHbrium conditions prevail. In this event crystallisation is not completed at 1455°C, but continues along the C A—C2S boundary until the iavariant poiat at 1335°C is reached. Crystallisation of C2S, C A, and then occurs to reach complete solidification. Such... 

The core function of QRA is to provide information for decision making. QRA results in and of themselves cannot prove anything. However, decision makers can compare QRA risk estimates to their own risk tolerance criteria to decide whether a plant or operation is safe enough. The same QRA results can support both the plant manager s contention that the plant is safe, as well as the community activist s claim that the plant is unsafe. The difference lies in the individual s risk tolerance, not the QRA. 

Let s consider one rather restricted structural optimization problem, that of a composite laminate. You have seen claimed as attractive advantages of composite structures the fact that we can orient the laminae in a laminate to our heart s content to try to get the most efficient structure. This characteristic is totally unlike what is possible with metal structures. This laminate orientation flexibility is certainly an advantage, but how do we use it ... 

Although the indicated temperature had risen, the temperature of the reactor s contents had not. Pump J2, running with a closed suction valve, got hot, and the heat affected the temperature point, which was close to the pump. 

A BLEVE s effects will be determined by the condition of the container s contents and of its walls at the moment of container failure. These conditions also relate to the cause of container failure, which may be... 

The blast and fragmentation effects of a BLEVE depend directly on the internal energy of the vessel s contents—a function of its thermodynamic properties and mass. This energy is potentially transformed into mechanical energy in the form of blast and generation of fragments. 

The pressure and temperature of a container s contents at the time of failure will depend on the cause of failure. In fire simations, direct flame impingement will weaken container walls. The pressure at which the container fails will usually be about the pressure at which the safety valve operates. This pressure may be as much as 20 percent above the valve s setting. The temperature of the container s contents will usually be considerably higher than the ambient temperature. 

Leiber (1980) describes this accident, which occurred in Haltern, Germany, on September 2, 1976. A rail car carrying 231,000 kg (470,000 lb) (90% full) of carbon dioxide exploded. The tank s contents were at 100 psi (7 bar) pressure and - 15°C (5 F) temperature. At the moment of the explosion, the car was passing through a railroad shunting yard in Haltern at a speed of about 16 km/h (10 mph). 

Results have been presented on one experiment. It involved a 5.659-m vessel containing 1000 kg of butane with a fill ratio of 39%. The vessel s contents were heated to 99°C, which is near but still below the supetheat-limit temperature, producing an internal pressure of 14.6 bar gauge. Vessel failure was then initiated. Measured pressure-time histories indicated that a number of separate pressure pulses occurred. They are plotted in Figure 6.6 as the overpressure-time relationship measured at 25 m from the vessel. 

The rapid expansion of a vessel s contents after it bursts may produce a blast wave. This expansion causes the first shock wave, which is a strong compression wave... 

In this section, three methods for calculating the blast parameters of pressure vessel bursts and BLEVEs will be presented. All methods are related that is, one basic method and two variations are presented. The choice of method depends upon phase of the vessel s contents and distance to the blast wave s target, as illustrated in Figure 6.19. 

The application of information in Figure 6.19 requires some explanation. The decision as to which calculation method to choose should be based upon the phase of the vessel s contents, its boiling point at ambient pressure T its critical temperature Tf, and its actual temperature T. For the purpose of selecting a calculation method, three different phases can be distinguished liquid, vapor or nonideal gas, and ideal gas. Should more than be performed separately for each phase, and the... 

The total energy of a vessel s contents is a measure of the strength of the explosion following rupture. For both the statistical and the theoretical models, a value for this energy must be calculated. The first equation for a vessel filled with an ideal gas was derived by Brode (1959) ... 

The reaction is frequently carried out in the presence of scrap iron (with low P and S content) to produce ferrosilicon alloys these are used in the metallurgical industry to deoxidize steel, to manufacture high-Si corrosion-resistant Fe, and Si/steel laminations for electric motors. The scale of operations can be gauged from the 1980 world production figures which were in excess of 5 megatonnes. Consumption of high purity (semiconductor grade) Si leapt from less than 10 tonnes in 1955 to 2800 tonnes in 1980. 

The oil industry frequently uses stainless steels or exotic bonded alloys for the processing of crude oil in the temperature range 200-600°C. These materials are very expensive and there is a strong economic incentive for finding cheaper alloys which are resistant to HjS and some gaseous organic sulphides arising from the S content of the crude oil". ... 

N 24.12% brick red solid mp, decomps when heated over 300°. Insol in w and the usual organic solvents as well as weak acids and alkalies. Comm prepn (Ref 3) is from thiocyanic acid and/or thiocyanates either by anodic oxidation or by interaction with hydrogen peroxide or halogens. The yield is impure because it contains both H and O. The S content varies between 45 and 55%. Lab prepn of the pure polymer is by reacting the Na salt of 5-chlor-3-mercapto 1,2,4-thiodiazols with either acet, ethanol or w (Refs 1 2)... 

To check the identity and purity of the products obtained in the above reactions it is not sufficient to analyze for the sulfur content since a mixture may incidentally have the same S content. Either X-ray diffraction on single crystals or Raman spectra of powder-like or crystalline samples will help to identify the anion(s) present in the product. However, the most convincing information comes from laser desorption Fourier transform ion cyclotron resonance (FTICR) mass spectra in the negative ion mode (LD mass spectra). It has been demonstrated that pure samples of K2S3 and K2S5 show peaks originating from S radical anions which are of the same size as the dianions in the particular sample no fragment ions of this type were observed [28]. 

Cell membranes are not simply passive containers for the cell s contents. Rather, they are highly organized, dynamic, and stractiirally complex biological systems that regulate the transfer of specific chemicals throngh the cell wall. 

Compressed gases, therefore, present a unique hazard from their potential physical and chemical dangers. Unless cylinders are secured they may topple over, cause injury to operators, become damaged themselves and cause contents to leak. If the regulator shears off, the cylinder may rocket like a projectile or torpedo dangerously around the workplace. Other physical hazards stem from the high pressure of a cylinder s contents, e.g. accidental application of a compressed gas/air hose or jet onto an open cut or wound, whereby the gas can enter the tissue or bloodstream, is particularly dangerous. 

We are given temperature data and information about the calorimeter s contents ... 

A more detailed description of this section s contents can be found in Saraiva (1993) or Saraiva and Stephanopoulos (1992d). 

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