Hubert H. Humphrey took nine years to get through the University of Minnesota. But they're carving his name in granite there all the same.

Yesterday the Minnesota senator waxed nostalgic about his college days "when I wrote all kinds of papers and entered contests for the prize money, then the old dean said I couldn't have it until graduation. I told him I needed it then, to stay in school."

His audience at a luncheon at the Hay-Adams Hotel was a group of wealthy Minnesota businessmen and friends. They chuckled appreciatively, then reached for their checkbooks. By the time the soup course was over, $2.3 million, "plus some smaller contributions," had been pledged.

The money is not for the Humphrey's tuition, which the senator paid himself by working in a boarding house and going back to the family drugstore to help out when things got tight at home. It is to establish the Hubert H. Humphrey Institute of Public Affairs on the Minnesota campus.

The goal of the drive that began yesterday is $22 million, an amount comparable to that which financed the Lyndon B. Johnson School of Public Affairs in Austin, Tex. The Humphrey school, which will be an extension of Minnesota's present School of Public Affairs, will be officially named for the senator next summer.

The Humphrey institute will be, if funds are secured, "on the scale" of the Johnson school, according to funding drive chairman Irving S. Shapiro.

Shapiro, chairman of the board of E. I. du Pont de Nemours & Co. also happens to be a graduate of the University of Minnesota. So are Vice President Mondale and junior Sen. Wendell Anderson of Minnesota, who were also at the Hay-Adams yesterday.

They lauded, in Mondale's words, "the two great institutions of our state - the university and Hubert Horatio Humphrey."

Humphrey was late, but nobody seemed to mind. The 66-year-old politician looked fit despite his recent bout with cancer. He said he had been "slipping and sliding around the Hill like these were banana peels under me."

He was late, Humphrey said, because "the Senate and the President are having a little trouble with foreign policy." For one of the few times in his life, he did not elaborate.

Instead Humphrey talked about the early days of his marriage. His wife, Muriel, sitting beside him, smiled broadly when Humphrey recalled "That was before the days of federal grants for college students," he said. "So I married my scholarship."