וְֽאֶת־חַטַּאתְכֶ֞ם אֲשֶׁר־עֲשִׂיתֶ֣ם אֶת־הָעֵ֗גֶל לָקַחְתִּי֮ וָאֶשְׂרֹ֣ף אֹת֣וֹ ׀ בָּאֵשׁ֒ וָאֶכֹּ֨ת אֹת֤וֹ טָחוֹן֙ הֵיטֵ֔ב עַ֥ד אֲשֶׁר־דַּ֖ק לְעָפָ֑ר וָֽאַשְׁלִךְ֙ אֶת־עֲפָר֔וֹ אֶל־הַנַּ֖חַל הַיֹּרֵ֥ד מִן־הָהָֽר׃
我把你們所犯的罪，就是你們所造的那牛犢，拿來用火焚燒，又把它搗碎，磨得極細，直到細如塵土；我就把那塵土撒在從山上流下來的溪水中。
Rashi
טחון — This is a present tense of continuous action like הלוך וכלות “going on destroying”; moulant in O. F. English grinding (cf. Rashi on Deuteronomy 3:6).
Ibn Ezra
your sin denotes the calf, and Scripture proceeds to clarify that, by specifying the appositive the calf.
Ramban
AND I CAST THE DUST THEREOF INTO THE BROOK THAT DESCENDED OUT OF THE MOUNT. He did not mention that he made them drink [of the water mixed with the dust of the calf]143See Exodus 32:20. by way of humiliating them for their deeds,144The Hebrew reads: “by way of their honor” — but it is a euphemism. See Vol. II, p. 563 (on top): “disgracing their deeds by grinding etc.” because he did not want to tell them that he had done to them what is done to wives suspected of adultery.145Numbers 5:16-22.