The phrase "expound for" is correct and can be used in written English.
It means to explain or clarify something in depth or with additional detail. Example: In his speech, the professor expounded on the reasons for the economic crisis, providing historical context and statistical data to support his arguments.
Instead, I listened to him expound for a while on the popularity of Ricky Martin, what it meant for popular music, for ethnic culture, even sexual politics.
In a subsequent meeting with the real power behind the throne, Obama invited Vladimir Putin to expound for an hour on what hadn't worked in recent Russian-American relationships, before responding.
But if that is so, he has not sold the message to New Jersey voters, And it is a bitter irony that a man who can expound for hours on the theology of Reinhold Niebuhr or the esoterica of prescription drug plans has not been able to explain something far more basic for New Jersey voters: himself.
In this paper we expound, for the first time, the application of the Strength Pareto Evolutionary Algorithm to the Multi-Objective design of isolated hybrid systems.
He can expound for hours on the merits and drawbacks of electronic health records.
That history meant something to Yoakam, whose musical knowledge runs deep enough that he can expound for 15 minutes on the provenance of the studio's linoleum floors.
Yet, doctrines are not expounded, for this is a book of the songs of Israel that describe the way Yahweh was experienced and worshipped.
Caedmon later composed verses based on Scripture, which was expounded for him by monks at Streaneshalch (now called Whitby), but only the "Hymn of Creation" survives.
He expounds for several minutes on the excellence of the article, but he has to open the magazine to recall who wrote it.
"I'm a cripple," Mr. Lopez said, and then expounded for several minutes on how as a slow-moving pedestrian he felt endangered by the proliferation of cyclists on streets and sidewalks.
In his numerous commentaries on Aristotle's logical works, he expounded for the first time in Arabic the entire range of the scientific and nonscientific forms of argument and established the place of logic as an indispensable prerequisite for philosophic inquiry.
