CALCIUM AMMONIUM NITRATE& PRILLED POROUS AMMONIUM NiTRTATE (PPAN): A CRITICAL REVIEW
One of the
curious researchers and user of ANFO asked a very interesting question. His
question is - is it viable to replace AN with CAN in standard ANFO formulation?
The second part of his question is - what is its impact on
performance/Fuel (diesel) absorption in case of grinding CAN & Caking
in storage?
My responses to your queries are as follows
Ammonium nitrate has its own different forms such as the AN, LDAN,
HDAN, PPAN, UAN, CAN, and so on. Many different products are manufactured from
these variants of AN. The newer products manufactured are available in the
forms of ANFO, HANFO, and LDSME. Also there are products like ANVO where the
fuel oil is vegetable oil.
We shall discuss some of the aspects of the ANFO nad our discussion will restrict to the question or ruery raised by one of the curious and innovation mind. His question is – is CANFO as good as the ANFO.
Let u see.
[1] ANFO is a straight jacket product. Any change in the input materials (AN and Fuel Oil) will make it a new product, and the product thus formed is no more ANFO.
[2] Calcium ammonium nitrate (CAN) is solid and non-porous. The product using CAN and Fuel Oil may be called - CANFO.
[3] The density of the CANFO could be somewhere in the range of 1.0 to 1.1 g/cc. The density of ANFO you know is in the range of 0.78 to 0.82 g/cc. So, CANFO will lose cost competitiveness (from the viewpoints of the user mining industry). Secondly, CANFO may yield insufficient gaseous energy as well as less heat energy.
But there are silver linings. The underlying benefits are the cost and performance with an equivalent product to ANFO. Here are some of these points:
[a] Keep using LDAN, but change the Fuel Oil.
[b] The potential but cheaper fuel oils are LDO and Recycled
Engine oils. Make sure that you get these oils from reliable sources like HPCL,
BPCL, HEMM departments of large mines, and so on.
[c] Always insist on MSDS from the manufacturers and suppliers for
the LDO and recycled engine oils. Ensure that the supplied oils pass at least
two parameters, namely, (i) the density, and (ii) the flashpoint. Density is
important for the performance of the product, and the flashpoint is important
for safety in the manufacturing of the ANFO.
[d] The cost of LDAN is going to touch Rs.50,000 per ton in the
next couple of months and may hover around in this range for quite some time.
So, it is wise to change the “straight jacket ANFO” into a Tailor-Made ANFO”.
By doing this, one can save costs. The name and the energy are unchanged.
[e] The concept and the use of aluminum powder in ANFO is an old
one. This product is known as – AlANFO. The only disadvantage with this product
is that it reduces the VoD of the product. Heat energy goes up, but gaseous
energy will come down.
I have been working to develop and establish different types of ANFO for one of the explosives manufacturers. The newer versions are as follows: (a) Water Resistance ANFO or WRANFO, (b) Tailor-Made ANFO, which means the cost and energy are designable suitings to the needs of the customer or of the strata in the rock blasting operations, and (c) ANFO with different types of fuel oils.
Should you need further help, clarity, or hand holding I would be happy to do the same for you. By the way, I take up project base consultancy too.
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