Fertilizers, compound consumption

World consumption of potassium salts presentiy exceeds 28 million t of K O equivalent per year. About 93% of that is for fertilizer use (see POTASSIUM compounds). The potash [17353-70-7] industry is essentially a mining and beneftciation industry. The two main fertilizer materials, KCl and K SO are produced by beneftciating ores at the mine sites. The upgraded salts then are shipped to distributors and manufacturers of mixed goods. 

Sulfur [7704-34-9] S, a nonmetallic element, is the second element of Group 16 (VIA) of the Periodic Table, coming below oxygen and above selenium. In massive elemental form, sulfur is often referred to as brimstone. Sulfur is one of the most important taw materials of the chemical industry. It is of prime importance to the fertilizer industry (see Fertilizers) and its consumption is generally regarded as one of the best measures of a nation s industrial development and economic activity (see Sulfur compounds Sulfurremoval and recovery Sulfuric acid and sulfur trioxide). 

Sulfur (qv) is among the most widely used chemicals and often considered to be one of the four basic raw materials of the chemical iadustry. In 1993, worldwide production of sulfur reached 55 million metric tons (1). Production of sulfuric acid consumes the vast majority (- 90%) of sulfur (2) (see Sulfuric acid and sulfur trioxide). This acid is a steppiag stone ia the production of other sulfur-containing compounds, most notably ammonium sulfate fertilizer which accounts for 60% of the total worldwide sulfur consumption (2) (see Ammonium compounds Fertilizers). 

There has been some speculation that estrogenic compounds may adversely affect the fertility of men by reducing testosterone levels and sperm counts (Atanassova et al, 2000). To date, however, the limited information available suggests that consumption of phytoestrogens does not affect reproductive hormones or semen quality (Nagata, 2000 Nagata et al., 2001 Mitchell et... 

The consumption of ureaform in the United States is approximately 75,000 tons/year, not including that formed in compound fertilizers from solutions. Most of the production goes into compound fertilizer for specialty uses, such as for lawns, flower gardens, and golf courses. The wholesale price of ureaform per unit of nitrogen is about three times that of urea, ammonium nitrate, or ammonium sulfate. 

Research on controlled-release nitrogen sources is in two broad categories the synthesis of nitrogen compounds with desired solubility characteristics and the application of protective coatings on soluble nitrogen fertilizers. Examples of synthesized compounds that dissolve slowly are urea-formaldehyde products, isobutylidene diurea, and crotonylidene diurea. However, the relatively high cost of these products tends to limit their consumption to specialty uses. 

There are a considerable number of stable crystalline salts of the ammonium ion [14798-03-9] NH. Several are of commercial importance because of large scale consumption in fertilizer and industrial markets. The ammonium ion is about the same size as the potassium and mbidium ions, so these salts are often isomorphous and have similar solubiHty in water. Compounds in which the ammonium ion is combined with a laige, uninegative anion are usually the most stable. Ammonium salts containing a small, highly charged anion generally dissociate easily into ammonia (qv) and the free acid (1). At about 300°C most simple ammonium salts volatilize with dissociation, for example... 

The estimated unit consumptions (not including raw materials) for the four compound fertilizer production processes are summarized in Table 16.9. Using these unit consumptions and typical mid-1995 U.S. costs, the conversion cost, based on a production of 120,000 tpy, including bags and bagging but not raw materials, varies from about US 26/tonne for bulk blending to about US 63/tonne for chemical granulation. In all cases fixed... 

Typical production formulas (raw material consumption) for an NPK 15-15-15 produced by the four processes are shown in Table 16.10. It is difficult to precisely evaluate the cost of raw materials for the four compound fertilizer production processes examined because of large variations in prices caused by... 

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