Whether ashes from burning impurity is impure
3-1-2018 | IslamWeb
Question:
Assalaamu alaykum. My question is regarding ashes after burning an impure thing: are the ashes of an impure thing (for example, a piece of paper contaminated by pig gelatine or alcohol) impure, or has it become pure through being burned?
And my second question is: if a person's name is Abdul-Khaaliq or Mohammad and he carries an ID card with his name on it and he drinks alcohol while his ID card is in his pocket, would that be considered disbelief?
Answer:
All perfect praise be to Allah, the Lord of the worlds. I testify that there is none worthy of worship except Allah and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and Messenger.
As for your first question, the scholars held different opinions regarding the impurity that has transformed into a different substance and whether it becomes ritually pure as a result or not. The preponderant view is that it becomes ritually pure. This was the opinion chosen by Shaykh Al-Islam Ibn Taymiyyah and held preponderant by Shaykh Ibn ʻUthaymeen 
both. So if the dead animal or the like of impurities is burned and turns to ashes, it becomes ritually pure according to this view.
Tabyeen Al-Haqaa'iq reads:
"An impure substance becomes pure by transformation to another substance according to our school of Fiqh. For example, if a dead animal falls into a vessel filled with salt and is transformed into salt, or the excrement is transformed into dust or burned with fire and turns into ashes, they become pure. This is similar to alcohol turning into vinegar or the tanning of the dead animal's skin (the process in which leather is made). Ibn Taymiyyah 
underlined in his book Al-Fataawa that if the dead sheep's head is burned until all blood is removed from it, it is judged to be pure. The same ruling applies to the impure moisture in a furnace, it is purified by fire."
Accordingly, if the pig is transformed into dust, for instance, this dust is declared ritually pure.
As for your second question, this person is not accused of disbelief if he did not intend to disrespect the Name of Allah; rather, he is a sinner and bears a sin for what he committed (drinking alcohol).
Allah knows best.