Products Manufactures from Phosphorus

4 Products Manufactures from Phosphorus Diphosphorus(V) oxide 

About 85% of the white phosphorus produced is burnt to diphosphorus(V) oxide. 

This is mainly directly hydrolyzed to phosphoric acid. Only several thousand tons of diphosphorus(V) oxide are produced annually worldwide. In the USA the capacity for diphosphorus(V) oxide is currently ca. 7 10- t/a, which is largely directly utilized. 

Diphosphorus(V) oxide is produced using burners similar to those used in the production of phosphoric acid. Here dry gas has to be used, the walls of the combustion chamber being cooled in a so-called barn , a large settling chamber in which ca. 95% of the diphosphorus(V) oxide formed is condensed. At temperatures between 170 and 200°C a denser and more crystalline product is obtained than when the chamber is water-cooled. The tail gases which contain diphosphorus(V) oxide can, for example, be utilized in a phosphoric acid plant. 

Applications Diphosphorus(V) oxide is used as a drying agent, in dehydration reactions in organic chemistry, for the improvement of the properties of asphalt, and in the manufacture of surface active substances for plastics and lubricating oil additives. 

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The phosphate manufacturing and phosphate fertilizer industry includes the production of elemental phosphorus, various phosphorus-derived chemicals, phosphate fertilizer chemicals, and other nonfertilizer phosphate chemicals [1-30], Chemicals that are derived from phosphorus include phosphoric acid (dry process), phosphorus pentoxide, phosphorus penta-sulfide, phosphoms trichloride, phosphorus oxychloride, sodium tripolyphosphate, and calcium phosphates [8]. The nonfertilizer phosphate production part of the industry includes defluori-nated phosphate rock, defluorinated phosphoric acid, and sodium phosphate salts. The phosphate fertilizer segment of the industry produces the primary phosphorus nutrient source for the agricultural industry and for other applications of chemical fertilization. Many of these fertilizer products are toxic to aquatic life at certain levels of concentration, and many are also hazardous to human life and health when contact is made in a concentrated form. 

The manufacture of phosphorus-derived chemicals is almost entirely based on the production of elemental phosphorus from mined phosphate rock. Ferrophosphorus, widely used in the metallurgical industries, is a direct byproduct of the phosphorus production process. In the United States, over 85% of elemental phosphorus production is used to manufacture high-grade phosphoric acid by the furnace or dry process as opposed to the wet process that converts phosphate rock directly into low-grade phosphoric acid. The remainder of the elemental phosphorus is either marketed directly or converted into phosphoms chemicals. The furnace-grade phosphoric acid is marketed directly, mostly to the food and fertilizer industries. Finally, phosphoric acid is employed to manufacture sodium tripolyphosphate, which is used in detergents and for water treatment, and calcium phosphate, which is used in foods and animal feeds. 

There arc two main processes for the industrial production of phosphoric add, H3PO4. from phosphate rock (1) the wet process which involves tlie reaction of phosphate rock with H2SO4 to yield phosphoric acid and insoluble calcium sulfites, Several of the impurities present in the rock dissolve and remain with the product add. These are not important when the add is used for fertilizer manufacture. However, the impurities are deleterious to the manufacture of phosphorus chemicals. For a purer product, (2) the furnace process is used, wherein the phosphate rock is combined with coke and silica, producing elemental phosphorus as previously described. Oxidation of the phosphorus produces P2O5 which, when combined with H2O, yields H3PO4. 

Shaft Furnaces The oldest and most important application of the shaft furnace is the blast furnace used for the production of pig iron. Another use is in the manufacture of phosphorus from phosphate rock. Formerly lime was calcined exclusively in this type of furnace. Shaft furnaces are widely used also as gas producers. Chemicals are manufactured in shaft furnaces from briquetted mixtures of the reacting components. 

The production of phosphorus trichloride from phosphorus and chlorine is an important step in the manufacture of a number of agrochemical products. Raman spectroscopy has been used to monitor the reaction and control the raw material feed rates. This maximises production of phosphoras trichloride, minimizes the formation of phosphorus pentachloride and ensures safe operation when plant shut-down periods are needed. Remote analysis is achieved using optical fibers to provide a safer operation and a more rapid analysis than was previously possible [29, 30]. 

The only major bulk chemical not so far considered is phosphoric acid, which can be manufactured pure from phosphorus and in an impure form from phosphate rock. The latter process is the dominant one, the impure product being used mainly in the preparation of fertilizers. Phosphate rock is also the most common source of elemental phosphorus. It is extracted by open-cast mining. The thermal process for producing phosphoric acid from the element produces an acid which is about three times more expensive than that produced direct from phosphate rock using the so-called wet process. 

In Asia, oriental noodles play an important role in the diet. Similar to pasta products, oriental noodles manufactured from wheat flours are considered an important source of calories. Practically all the caloric load is supplied by starch and gluten proteins. Alkali noodles contain significant amounts of potassium carbonates, bicarbonates, and phosphates used to impart typical flavors, aroma, texture, and colors. These salts increase sodium, phosphorus, and potassium levels. Wonton or egg noodles contain higher protein content, quality, and overall nutritional value due to the addition of whole eggs. 

All phosphorus fertilizers come from wet process phosphoric acid or directly from phosphate rock. Normal superphosphate, triple or concentrated superphosphate, and ammonium phosphate are the three common types used. Normal or ordinary superphosphate (NSP or OSP) is mostly monocalcium phosphate and calcium sulfate. It is made from phosphate rock and sulfuric acid and is equated to a 20% P2O5 content. It led the market until 1964. The production of normal superphosphate is similar to that for the manufacture of wet process phosphoric acid (Chapter 2, Section 3) except that there is only partial neutralization. Normal superphosphate is no longer used to any great extent. The following reaction is one example of an equation that represents this process. 

The aroma compounds from the tropical fruits described in this chapter can be very important for consumers and industry as they are exotic and extremely pleasant however, the production of these compounds by biotechnological processes should be emphasised since the extraction from the fruits is a hard task. Many tropical soils contain less nitrogen and phosphorus, have lower capacity to absorb fertilisers, and therefore have lower conventional productive capacity, but some tropical soils have been very intensively farmed and further intensification is possible in other areas. Thus, the evaluation of a sustainable agriculture in tropical regions requires a sophisticated approach including the estimation of the risk of microbial or insect infestations. As many fruits go directly to fresh markets or to immediate processing, a continuing supply of the flavour manufacturers in the future is not completely assured. 

Applications of Sulphur.--Much sulphur is consumed in the manufacture of matches, being applied in the form of phosphorus sulphide as a constituent of the heads of common friction matches, whilst on the Continent the wooden splints have frequently been treated with sulphur to facilitate the passage of the flame from the bend to the remainder of the match. Large quantities of sulphur are also required for the production of gunpowder and fireworks for these purposes finely divided sulphur is necessary, but u flowers of sulphur is not suitable on account of its liability to contain tract s of sulphuric acid, due to atmospheric oxidation, which would render its use dangerous. 

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