The **standard issue of urea pellet strength
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The urea **standard (GB2440—2001)** sets clear requirements for parameters such as total nitrogen, biuret, moisture content, particle size, and color. However, since there are no requirements regarding particle strength, I wonder if the urea products used by you all have undergone strength analysis? If it has been analyzed, what are the specific figures? Also, have you come across any corporate standards regarding the strength of urea pellets, or are there similar standards abroad?
Our company analyzes it once a week (at the bottom of the granulation tower): 1 with formaldehyde at 5.0 N, 2 without formaldehyde at 3.0 N. For urea**, there is indeed no specific strength standard; it seems like it isn’t necessary Only screening needs to be checked; if the strength is low, the screening quality will decline during transportation.
The purpose of adding formaldehyde to urea is to improve particle strength. However, according to the comparisons provided by the moderator of the Five Lakes Boating forum, the strength doesn’t differ much whether formaldehyde is used or not, right? After adding formaldehyde, its strength should increase quite a bit! Please, Heyou, continue the discussion. It would be even better if a more authoritative source could be found to support it!
Formaldehyde reacts with urea to produce MMU (monohydroxymethyl urea), and then a small amount of MMU is mixed with urea solution to create larger urea particles; as a result, the strength of such urea is much higher than that of urea produced directly from urine. The specific compressive strength is: 2.5 mm corresponds to a minimum of 2 kg per minute, while 6.3 mm corresponds to a minimum of 6 kg per minute. Those who understand this data may understand better.
We analyze it once per shift (for large particles); add formaldehyde at 25–35 N. **There is no strength standard for urea.**
Hehe, large particles are indeed different – compared to our small particles, their strength is nearly ten times greater. Without formaldehyde, it would be 2–3N lower; I initially mentioned a higher value, and after adding formaldehyde it’s basically around 5.0–5.1N. The screening is much better, and there is significantly less dust. This might be related to our nozzles.